1. yo mama so stupid she took a ruler to bed to see how long she slept.
2. yo mama so fat that when god created light he asked her to move.
3. yo mama so stupid she got locked in a grocery store and starved to death.
4. yo mama so old she was the waitress at the last supper.
5. yo mama so old her social security number is 1.

1,3,5 are my favorite... must use them in COD

I like the first one. The rest of them I have heard before.