A few years ago there was a popular series of humor books starting with "Snaps". It had a whole bunch of "yo' mama" type insults in it ("your mama is so fat she uses a satellite dish for a diaphragm"), and then went on to describe playing "the dozens". Read more about it here.
Here's a taste:
Yo' mama is so fat:
she uses a satellite dish for a diaphragm.
when she dances the band skips.
her blood type is Ragu.
when she wears heels she strikes oil
Your sister is so fat:
they had to baptize her at Sea World.
they took her baby pictures by satellite