South Park: Bigger, Longer & Uncut (1999)

Continuity mistake: During the "La Resistance" number, during the verse, "They may stab you in the head, with a dagger or sword," We see a guy wearing blue with a blue hat on the left (probably Craig). In the next shot, he disappears, and in the next shot, he reappears. (00:50:05)

Cartman: Don't call me fat, you fucking Jew!
[Gasp from the class.]
Mr. Garrison: Eric! Did you just say the "F" word?
Cartman: [confused.] Jew?
Kyle: No, not Jew! He's talking about "fuck"! You can't say "fuck" in school, you fucking fat ass!
Mr. Garrison: Kyle!
Cartman: Why the fuck not?
Mr. Garrison: Eric!
Stan: Dude, you just said "fuck" again!
Mr. Garrison: Stanley!
Kenny: [Muffled.] Fuck.
Mr. Garrison: Kenny!
Cartman: What's the big deal? It doesn't hurt anybody. Fuck fuckety fuck fuck fuck.
Mr. Garrison: How would you like to go see the school counselor?
Cartman: How would you like to suck my balls?
[Gasp from the class.]
Mr. Garrison: What did you say?
Cartman: I'm sorry. I'm sorry. Actually, what I said was...
[Cartman pulls out a bullhorn.]
Cartman: HOW WOULD YOU LIKE TO SUCK MY BALLS? MR. Garrison.
Stan: Holy shit, dude.

Trivia: In the scene at the United Nations, the US Ambassador claims that Terrance and Phillip will be put on trial for "corrupting America's youth" - a charge similar to that levied against Socrates. (00:24:40)

Question: When Cartman says he saw Kenny, Kyle says he sees Kenny everyday, on the face of every child, on the smile of every baby and he and Stan starts laughing. What does the joke mean?