Must be a one-liner type burn such as, "Yo momma so fat..." etc. Let's see how many we can come up with besides someone gets really bored
Maybe later when it starts to die out I might let in other burns, comebacks, etc, besides those one-liners.

I am a nobody, and nobody is perfect, therefore I am perfect.

"wheres Your Fouton!!!"

how does it feel to suck

I know exactly how you feel everyone at my school says that. An there is the one group of faggot ass kids that think it is like the coolest comback ever. Even funnier I was in class with one of em an there talkin to each other about getting cigarettes for the weekend so I asked em if they ever smoked pot an they go no man only cigarettes but I wanna smoke pot. An I was like you fuckin faggots think your all hard an you havent even smoked weed? It was funny though cas they were whispering about cigarettes.

But anyway hear is a decent your mom joke. Your momma walked outside in a red rain coat an I yelled KOOOOOOOOLLLLL AID!!!!!!!!!

i kno wat u meen palm3r,theres a faggot ass boy at me skool like that ill be talk to my friends and outta kno wher Your mom

I heard this one:

"Yo' momma's so ugly that she made an onion cry."

And then there's this one, which actually belongs to my sister. Lol.
(We're just joking with each other, btw)
Me and my sister were watching TV and she said, "I think I'm going to go take a really hot shower." I said, "Thank god... Maybe it'll get the stench off, finally." And she said, "Maybe it'll get your mom off, FINALLY!!!" =P

I once heard someone angrily yell at another student:

"AT LEAST I'M NOT A BOTCHED ABORTION!",

which promptly made her run out of the classroom crying.

Also, speaking of burns concerning abortion, I heard this one before, but jokingly: "What's your stance on paying for sex? 'Cause I promised your mom the free abortion she couldn't get 19 years ago" (between guys my age).

you suck ojn the 14 dicks of failure