Food stamps

Joke: Yo mama so stupid, she took a picture of some food, stamped it, and tried to use it as food stamps.

Joke: Yo mama's so fat, she made Weight Watcher's go blind.

Joke: Yo mama's so ugly, when she plays Mortal Kombat Scorpion tells her "Stay over there!"

Joke: Yo mama's so poor, when she goes to KFC she licks other people's fingers.

Joke: Yo mama's so stupid, she put a peephole in a window.

Joke: Your mama is so fat that her belt size is equator.