but the challenge is you can't smile or laugh while watching.

Why not?

(Finebros) That's the whole point; it's a challenge.

You laugh or smile, you lose. Here we go.

Okay.

So I'm not... I can't... I can't laugh?

(Finebros) Or smile.

Or smile?

(takes a breath) Now I'm smiling already.

I'm gonna go to my dark place.

(cracking jawbone)

Warming up the jaw.

(Finebros) All right. Here we go!

(bleep)

♪ (men vocalizing "The Blue Danube") ♪

God, it's so perfect.

Gotta take a deep breath.

This is really difficult... to not laugh at this.

Is it gonna be five minutes of this guy... air humping?

I've seen this too many times to be funny.

Nothing funny about that.

I've cracked it. I've got the technique down.

It's not getting me.

(arguing in foreign language)

(laughs)

Bro, come on, come on, dawg.

(laughs)

I think I'm gonna win this challenge.

(laughs)

You can't... That is insane.

(laughs)

(Finebros) So close. After it ended?

I don't know. I can't hold it.

Look. I haven't laughed yet.

(video) Come on, let me see your face!

Oh, is it PewDiePie?

You're gonna ask me to not laugh at PewDiePie?

(man in video laughing)

How do you not smile at that, bro?

It's a goat, it's a goat flying away...

(laughing in video continues)

Poor goat, he didn't deserve that.

It's always exceptionally hard not to laugh when somebody

else is laughing, but even worse when it's PewDiePie.

I think, I think I'm technically smiling right now. (laughs)

(Finebros) Also, not PewDiePie.

It's not PewDiePie?

(Finebros) But it's someone else who's Swedish.

What game is this?

What's making me wanna smile

is you guys holding in your laughter.

If I just maybe do this?

(video) Laddergoat, you're so random.

I think I've heard that phrase before...

"Laddergoat, you're so random."

(breaths out) Okay...That was a close one.

- (baby chuckling) - Oh no... Oh no...

Ugh, no!

(man in video chuckling)

(man laughing oddly)

I'm in hell right now.

- (man laughing boisterously) - Okay.

(laughs)

Okay. I think that's a smile right there.

How did this one get me, though?

- (woman chortling and snorting) - What? What is that?

(woman honking and chortling)

(Finebros) You did it!

Not funny!

I have no soul.

I didn't laugh a single time!

(Finebros) You were close a couple of times.

I know, I almost puked.

(Finebros) Did you find those videos funny?

Yeah, they were funny.

I actually did.

Hilarious. Hilarious.

What was that guy trying to do...? On the wall...?

Like how could that possibly have ended well?

In the first one, I trained myself not to laugh.

Which one was the first one?

Oh, yeah, yeah... That's old school.

I thought when I saw that one, I was like,

"You guys, you're not gonna have us..." But you got us.

I don't know why it was funny to anybody.

Did anybody laugh at that?

(Finebros) What do you think of the ladder goat?

Dude, I just like goats, man. That's not fair.

You expect video games to obey the laws of physics,

but when they don't, it's amusing.

I wish things were that funny to me, like,

if everything was that funny, life would be like a great place.

I wanna find out what game that is, just to find that goat,

so I can make it climb the ladder.

They didn't seem all that funny.

I guess it's interesting, because that's the same sort of area

as my videos.

A lot of people thought, like, when I was starting, and didn't

have my facecam... People were like, "Are you Laddergoat?"

Yeah, he's like a Swedish gamer.

I actually made a video with him.

Can you imitate one of the laughs you heard

from the laughter chain video?

I almost lost it with that dude, he was like...

(imitates laughter)

Hya-hya-hya-hya.

(raspy chuckling)

(throaty laughing)

(high-pitched giggling)

Ka-ka-ka-ka-ka-ka... (laughs)

(Finebros) Why is watching other people laugh

something that makes people laugh?

I don't know. Science maybe?

People that, like, have a very specific laugh make you laugh.

You just see people laughing, and then you're like,

"I wanna be laughing and having fun too!"

It's like when someone yawns, you yawn all the time.

Yeah, laughing is contagious. Why is laughing contagious?

There we go. See? We just case in point right here.

Someone's, like, crying or my friends start crying,

and they call me like... (imitates crying)

I'm just like, "I know, girl. I know. He's bad for you."

(Finebros) What is the technique you try

to make yourself not laugh?

Well, I failed pretty bad, so I guess I didn't have one.

Try to distract myself.

Just trying to, like hyperanalyze things

and think about them in a complicated way.

By being myself. I have no sense of humor.

I found trying to shove a fist in the mouth.

Yeah, you were doing that. You were really going for that.

I was sucking in my cheeks like that.

Like, I tell myself, "This is not funny.

You are not going to laugh."

So, it's almost like mind over body.

I try to think of the most awful thing in the world.

It's like working at a theme park for ten years

- or for life. - (Finebros laugh)

Like, think of something else. I was like, "Puppies. Rainbows.

- Biscuits. Gravy." - (Finebros) What about dead puppies?

Oh, oh. Too far.

- Oh, now I'm sad. - (Finebros) But that would help.

Why has the idea of "I bet you can watch without laughing"

- become an online thing? - Well, 'cause we want to laugh.

And we want to be made to laugh.

Watching isn't enough anymore. Let's make a challenge out of it.

Let's make a game out of watching.

I mean, anything with the "try not to laugh" tied to it

is probably gonna be something uplifting.

Why would you not want to watch something like that?

And then there are going to be the people like me

who take a challenge very literally and say,

"I'm not laughing at this. No way."

Like, that's something that everybody would click on,

'cause they're like, "Yeah, I can (bleeping) not laugh at that."

And then they feel like me who don't,

and then you pat yourself on the back.

(Finebros) Does it feel good to succeed?

It feels, actually, really sad,

'cause you guys are asking me questions like,

"Why didn't you laugh?" and then I'm like, "I don't know,"

and then I think about it in my head.

I'm like, "Why am I not laughing? Am I sad inside?

Am I just not having a good day?"

(Finebros) Is there a video out there

that just makes you laugh every time you see it?

- "Go! Bwaaah!" - "Go! Bwaaah!"

- "Washington." - "Single Ladies Clown Dance."

"Pretty much everywhere, it's gonna be hot."

This dude getting frisked by a cop,

and his pants are, like, sagging really low,

and then the cop reaches around and he's like, "What's this?"

And he's like, "That's my penis."

He's like, "Oh, your penis. All right, sorry." (laughing)

It's so funny!

(Finebros) And finally, the most important question of all:

- why do we laugh, anyway? - Stress relief.

'Cause we're uncomfortable.

(forced laugh)

(turns to weeping)

Oh, (bleep), that's deep. That's really deep.

Why do we laugh? Why do we cry?

Why do we bleed? Hmm?

I don't know, basically, is what I'm trying to say.

You guys, this is a deep question.

Write in the comments below. Why do we laugh?

Let's get the audience involved in this.

I think about that sometimes, believe it or not.

Like, when I'm laying in bed at night staring up at my ceiling,

I can't fall asleep. I'm just like...

(whispers) Laughing, like...

It's laughing and "I'm gonna die.

No matter what I do, I'm gonna die."

It's obviously a natural response, because even babies do it,

and we haven't taught them,

"Hey, this is what you do when something is funny."

I don't know and it's awesome.

I think laughter is one of those

things about people that makes us great.

Famine, starvation, terrible rape, terrible things--

all over the place,

but the fact that laughter is something

that we start doing at, like, 24 hours old--

it's nice.

Thanks for watching "YouTubers React."

New episodes of "YouTubers React"

comes out every other Thursday,

so make sure you subscribe to all of us.

The question is, what video makes you laugh the most?

Let us know in the comments below.

Question is, why do you have bare feet? That's the question.

- I'm airing them out. - I don't think it's appropriate.

We're on set, you've got your bare feet out.

Sometimes you gotta get loose.

I would appreciate it if you put your shoes back on.

- Well. (chuckles) - Bye.

Why are you still here? You haven't clicked anything yet.

Click something or leave.

Go on, click a box. Do something.

You're wasting your life.