Ok , you guys asked for the "Yo Mama" jokes , here we go :
Yo mama's so nasty, I called her up for phone sex and she gave me an ear infection
Yo mama's so nasty, she's got more clap than an auditorium.
Yo mama's so stupid, she got fired from the M&M factory for throwing away all the W's.
Yo mama's so ugly, her mom had to be drunk to breast feed her.
Yo mama's so ugly, she makes onions cry
Yo mama's so ugly, that if ugly were bricks she'd have her own projects
Yo mama's so old, she DJ'd at the Boston Tea Party