Original subtitles

-[all] …two, one. -[crashing]

[all yelling]

[Mark] This is me reclaiming my title

for the world's largest and tallest elephant toothpaste experiment.

And this is a different kind of reaction we discovered in all our experimentation

called devil's toothpaste,

which is insanely reactive

and super dangerous.

I'll explain why in a minute, but for now, here's a hint.

-[glass clattering] -[laughter]

Wow.

If you look closely in both shots, I'm not holding the trigger.

This kid is.

In fact, that kid was the whole reason we were there at all.

This was a culmination of eight months of planning

to throw him the most epic birthday party ever.

And all of this started inadvertently from a single surprise phone call.

[ringing tone]

What's up, Fletcher?

-Oh my God. -[laughs]

What's goin' on, buddy?

-You… What? -[laughs]

How are things, man?

They just got better.

[Mark] This is Fletcher.

And this is also Fletcher, a year before this call.

But unbeknownst to everyone at the time, also pictured here,

under all that amazing hair, was a fast-growing brain tumor.

They realized something was wrong

and discovered it was a dangerous form of brain cancer so rare,

he was only the sixth kid ever known to have had it.

So his family uprooted their lives for a year

and moved almost 1,000 miles to be closer to St. Jude,

where they removed the tumor and would try and fix his brain.

In fact, our call was the night before he was going back in

for another brutal week of chemo.

He's such a funny kid

that I was so inspired by his hopeful attitude that, after talking for an hour,

I secretly vowed that if he made it to 13 years old,

I would fly him and his family out

and surprise him with just the dopest birthday party ever.

And not long after, I texted Fletcher this picture.

So he knew we had closely matching hairstyles,

but what he didn't know is that plans were already underway

for him and I to take back the record

for the world's largest elephant toothpaste.

As a quick refresher, last summer, my buddy Science Bob and I

set the world record for elephant toothpaste

by filling up an empty swimming pool.

I wanted to be able to swim in the foam after,

so we figured out how to use yeast as the catalyst,

which is in fact safer, but it doesn't react very fast.

And our video seemed to inspire some folks because, two months later,

this happened in David Dobrik's backyard, where they didn't bother with yeast

and just took the normal reaction and scaled it up.

A few weeks later, these guys in Brazil did the largest experiment yet.

And they are the current Guinness World Record holders.

So even though Fletcher's birthday was eight months out,

we started testing right away

because I knew blasting a world-record amount of foam

straight up into the sky

wasn't as easy as it might sound.

The part that concerned me most was picking the right nozzle size.

Here's what I mean.

These three containers are identical except for the diameter of their outlets.

If that diameter's too large, it looks kind of cool

but it doesn't really go that high.

Too small, and it will go high

but it just looks like confetti and doesn't look that impressive.

But for every container, there's a Goldilocks-size diameter opening

that gives you that cool laminar-looking flow

while still going pretty high.

You might think, why don't you take a typical flask that works

and scale the dimensions up?

And we tried that on our first five-foot scale test…

[whooshing]

[Mark] And just as I feared, it went all confetti on us.

The problem is illustrated here.

If you scale up and double all the dimensions of the block, you get this.

It's perfect. All these dimensions increased exactly by a factor of two.

But wait a sec. The volume increased by a factor of eight.

This is the square-cube law. Its effects are everywhere in nature,

such as putting a hard limit on just how big land animals can be

because how heavy you are is a function of your volume,

but the strength of your muscles and bones

is a function of their cross-sectional area.

Since animals evolved to get heavier by the power of three

but stronger by only the power of two,

at some point, it's just too much.

So on the next test, we increased the top diameter

by a mere three and a half inches.

But the pendulum swung too far the other way

because while the column looked smooth, it didn't go that high.

And so, for the third test, we let the pendulum swing back just a tad

and shaved down that diameter by just over an inch

to try and dial in that Goldilocks outlet size.

And sure enough, the column went really high and looked great.

But this test uncovered another issue.

With such a high volume of foam,

the pressure was creating some really high forces in the flask.

I mean, that's a lot of damage.

Which, quite frankly, left us with only one option.

[dramatic music playing]

[Jon] Oh, yes!

[Mark] With the power of Flex Tape, we scaled up even further

to a ten-foot test,

and did our best to interpolate that Goldilocks outlet size.

-[man] Oh my God! -[woman] Ooh!

[laughter]

-[man] Oh my God! -[woman] Ooh!

-[man] Oh my God! -[woman] Ooh!

[laughter]

[Mark] Again, the outlet size worked great,

but our joint construction wasn't prepared for the further scaled-up forces.

In fact, score a fat W for the Flex Tape,

where you could see it singlehandedly held the thing together

even as the screws and wood busted through.

We were realizing we had to make the structure

so overengineered and indestructible

so the only option for the foam to escape the high pressure

would be going out the top.

While that wasn't a perfect result, I felt we'd learned enough from our failures

to design it strong enough for the final 20-foot world record version.

In the end, we ran over 150 tests,

not only to determine the right flask dimensions,

but things like, does neck length have an effect?

What happens if you vary the soap amounts?

What effect do different brands of food coloring have?

These tests were insightful, but perhaps the most interesting finding

was stumbling upon something I've affectionately named

devil's toothpaste.

You might be thinking, "Devil's toothpaste?"

"That seems a bit extreme." Allow me to demonstrate.

This is a box of the standard formula of hydrogen peroxide,

sodium iodide and soap

pretty much everyone uses to make elephant toothpaste.

Now here's the same volume of reactants

only this time using devil's toothpaste.

See if you can spot the difference in real time.

Not only is it hyperreactive, but the reaction is much hotter

so you get these really cool bubble formations.

Here's one more.

This is normal elephant's toothpaste in an Erlenmeyer flask.

No big deal. People have been doing this for years.

But once again, here's the same volume of reactants,

now only with devil's toothpaste.

[glass clattering]

[laughter]

Given how explosive this is, this may be irresponsible of me,

but while we watch the replay, I'll tell you how to make it.

You start with 26…

[bleep]

-Once that mixes, you're… -[bleep]

-…Oprah Winfrey… -[bleep]

…torch on the leftover rabbit fur, and you're good to go.

By taking some rigorous safety precautions,

we also intended to set the first and therefore only world record

for the world's largest devil's toothpaste experiment

by filling six 55-gallon drums

with 400 times the amount that broke the flask here.

So after 150 tests and eight months of work,

feeling more confident about our build plans and chemistry,

we packed everything up

and made our way to the small farming town of Gridley, California.

We chose Gridley because our friend Dale graciously agreed to let us use his land,

which is full of hundreds of acres of walnut trees.

No, don't even think about it, Phat Gus.

He also had a great backyard we could use.

With only four days till Fletcher was flying out for the party,

we got to work on a 20-second build montage.

[funky music playing]

[Mark] It took four consecutive 14-hour backbreaking days of labor in the hot sun

because with so much time to plan the most epic party ever,

I just kept adding more and more ideas to the list.

So in addition to the indestructible 20-foot flask

and devil's toothpaste mechanism,

we needed to make a methane bubble fountain,

a 3D bubble printer, a fire tornado,

a slip-n-slide into a pool

and an epic bubble pit.

Even though I brought my buddies,

it was cool to see this turn into a modern-day small-town USA barn-raising.

If we needed extra hands or equipment,

ten neighbors were there instantly to help us out.

The morning of the big day, there was last-minute scrambling,

but things were looking good.

I'm seriously so nervous right now.

I love pranks, and a surprise is the most wholesome type of prank,

so I haven't been able to sleep for days just thinking about this.

Like, every last detail to how this will go down.

With one hour left, we did one final test run on everything.

-First, the devil's toothpaste. -Two, one…

Perfecto.

And then the 20-foot flask.

For the real reaction, the peroxide would fill the whole bottom pool where Jon was,

and the troughs would dump over all the catalyst at once, like this.

Guinness only lets you choose one world record category per event.

We were going for the tallest,

but when we did the math to scale the flask

to the arbitrary height of 20 feet,

and this is a true story,

it was exactly one gallon less than the folks in Brazil

who set the world record for the largest.

So don't mind me while I set these two gallon containers right here.

As people started gathering for the surprise,

I hit the hardened streets of Gridley, California,

to look for some kind of last-minute disguise.

After a bit of a warm-up,

'cause these are moves I can do, and that's definitely me in the costume,

the moment I had spent eight months planning for had finally arrived.

The cover story for the kids

is they were coming to tour a walnut farm of a distant relative.

-[all] Surprise! -[party poppers popping]

-[cheering] -[woman] Whoo!

[Mark] To provide a juxtaposition,

I wanted him to feel as awkward as possible for this part.

[laughter]

[Mark] When we gathered for the picture, I snuck up behind him.

-I took off my mask. -[all] Cheese!

[Mark] All right. Cool.

What do you guys wanna do next?

-What should we-- -You're kidding.

-[laughter] -[Mark] Wha…

[Mark] His sister Isla also had no idea any of this was gonna happen.

[Mark] What up, buddy?

How are you? Get in here!

-I'm the bull-- -Mom.

[mom] Aw!

-What's up, dude? -[laughter]

When I'm not making videos, I'm the Gridley mascot.

You're the mascot?

To stretch out the surprise, I wanted him to think I was only there to say hi.

I had Dale suggest I take the kids for a ride in his dune buggy,

to which I reluctantly agreed, 'cause, you know, I'm a busy guy.

I could do it. Like, 15 minutes.

-You guys wanna go for a ride? -Yeah.

Is that cool? Let's get the crew. Your sister.

I had about, like, a half an hour, so…

-It's good to meet you in real life. -Yeah.

Yeah, let's go!

Whoo!

[cheerful music playing]

Don't tell Mom!

-Not a word. -Not a word, okay!

Watch out for walnuts.

-That's… Whoa! -Oh!

A single walnut grows in one of these, which is crazy to me.

All of those are a single walnut.

As we pulled up, I stopped the dune buggy in a precisely predetermined location

where the view of the flask was obscured by the truck.

-It's your birthday. I got you something. -[Fletcher] Tomorrow's my real birthday.

Oh, yeah, I'm one day off.

-That is so cool. -So, Fletch…

I've gotta, uh… I've gotta come clean, buddy.

You and I today are gonna set a Guinness World Record

for the world's tallest elephant toothpaste.

-Wait, what? -Are you kidding me?

You are currently in a YouTube video.

[Isla] Crazy!

I want you to wave to 20 million of your newest friends.

Hello! [laughing]

We're gonna put the elephant toothpaste in there and just blast it in the air.

-[mockingly] "Yeah, I got 15 minutes." -[laughs]

I actually fully cleared my schedule.

-Oh my God. -[laughing]

[Mark] With the surprise fully and successfully executed,

my heart rate finally lowered

and I gave him a preview of the cool stuff we had lined up for the party.

Then we headed to the backyard where he saw the setup and his mom.

You are devious!

At this point, it had sunk in there would be no walnut farm tour

and that her and I had been conspiring for months,

For now, it was time to party.

["Pata Pata" by Miriam Makeba playing]

[lyrics in Xhosa]

♪ And everybody starts to move ♪

♪ As soon as Pata Pata starts to play… ♪

Nice bubble party, Mark Rober.

♪ Whoo ♪

-♪ Whoo, whoo, whoo ♪ -♪ Hit it ♪

♪ Whoo ♪

-♪ Whoo, whoo, whoo ♪ -♪ Hit it ♪

[lyrics in Xhosa]

[Mark] Before we busted out the flaming bubbles or bubble pit,

we headed across the street to the world's first,

and therefore largest, devil's toothpaste experiment.

Here we go, Fletcher!

-Three, two, one! -[crowd] …two, one!

-Pull! -[pop]

-[whooshing] -[gasping]

[crowd] …two, one, pull!

-[gasping] -[Mark] Whoa!

-[gasping] -[Mark] Whoa!

-[gasping] -[Mark] Whoa!

[Mark] Whoa!

Yeah!

[Mark] Oh my God!

[man] Whoo-hoo!

Science Bob hooked us up with the slo-mo shot.

Whoa!

[gentle music playing]

[Mark] This shot was from a GoPro on rails.

We weren't fast enough with the pull.

And for some reason I found this WALL-E-level pathetically sad.

You can see even in slo-mo the reaction happens so incredibly fast.

[gentle music playing]

[Mark] I apologize for the gratuitous amount of slo-mo,

but this has got to be the coolest thing I've ever filmed.

And afterwards, it kept oozing this rainbow Play-Doh extrusion thing.

It just looked like some kind of whimsical alien landscape.

As you can see, over time it just sort of deflates itself.

After that, we went back, ate some dinner

and had some amazing, not at all creepy Army of Fletcher face cupcakes,

while the crew started prepping for the world-record finale.

In the vein of cool stuff I'd need at my birthday party if I was turning 13,

I, of course, had to bust out the Elon Musk flamethrower

to light fire bubbles.

And finally, back to the yard

to top things off with the most amazing bubble pit ever.

It was like belly-flopping on a cloud.

We realized it was taking way longer to fill than we had calculated,

so it was all hands on deck to pull this off before the sun went down.

Oh, and this is cool.

The bubble pit was dual-purpose, because, once empty,

it served as a bunker to give a completely safe front-row seat

to whatever was about to happen.

With the flask close to being filled,

Fletcher asked to take a ride in the Tesla 'cause he'd never been in one.

-I know this song. -This song.

-Okay. -This is in, like, every video.

-You guys are in a Mark Rober video. -Whoa!

Per the request, I gave them a quick ride.

[kids yelling and laughing]

[Fletcher] Oh my God!

-[boy] Can this-- -[Fletcher] Whoa!

-Oh my-- -Look out!

Autopilot.

Oh my God!

The weird part is I can sit and have a conversation with you,

and this feels very freaky.

But you trust… [yells]

Remember our story, all right?

-Yeah. -Ten miles an hour, tops.

[Mark] With the measurement drone in the air, our timing was perfect.

We made it back as they were sealing the door for the big moment.

-I'm handing this to you officially. -[all] Ooh!

To think, you should have been touring a walnut farm right now.

After eight months of planning and so much work by so many people,

the coolest birthday present I've ever given anybody

came down to this moment.

Here we go. Three, two, one.

[all yelling]

[yelling and cheering]

[gentle music playing]

It worked!

It went through the bottom!

That was so cool!

It came out the bottom. It lifted it up!

Look at my truck!

-Let's go. -[Isla] Oh my God!

What'd you think?

-So cool! -[boy] Insane.

-[Fletcher] Crazy! -[Isla] It exploded!

Look at the truck! It's, like, buried next to it.

[gentle ambient music playing]

-[gasping] -[Mark] Watch this.

Boom!

[walls cracking]

[gentle music playing]

[Mark] I'd like to point out how great that column looks,

with a perfectly-selected outlet diameter.

That is, until things got chaotic

once the pressure changed drastically from the big rupture.

We literally made a rocket ship.

Fundamentally, this is how rockets propel themselves.

The actual failure mode wasn't a floor strength issue

as much as it was a stiffness issue.

Our structure weighed over a ton.

I didn't consider that the reaction could lift the whole thing

five feet into the freakin' air.

At NASA, that's what we refer to as a critical oversight.

But this result was way more spectacular, plus it leaves room for improvement.

I should also note, even with all that,

we still crushed the previous world record by more than double.

And so, as the sun went down,

Science Bob lit up the fire tornado as a fitting end to the party.

I also told Fletcher there was one more thing.

With help from Dale,

he could use some heavy equipment to destroy our beautiful creation.

-[man 1] Whoa! -[man 2] Whoo-hoo-hoo!

[Mark] And so with that, the party was all over.

-That was epic. I'll never forget this. -[mom] Thank you.

[Mark] As they drove away, I thought about everything they'd been through

and all the people that came together from all across the country

to donate their time and energy for a kid they'd never even met.

And I might not vote the exact same as all of them,

but for, like, five inspiring days, none of that stuff mattered.

Whenever I find myself short on hope, I find it helps to put my phone down

and choose to see the good parts in my fellow humans

and be one of the good parts for my fellow humans to see.

And so, to Fletcher, thank you for being such a good example

of holding onto hope amidst really lame circumstances.

Happy birthday, buddy. And congrats on your new world record.