Yo mama is so dirty/greasy

Yo mama's so dirty, she has to creep up on bath water.

Yo mama's so dirty, she uses her dirty clothes as a weapon.

Yo mama's so dirty, the US Government uses her bath water for chemical weapons. 

Yo mama's so greasy, she sweats Crisco.

Yo mama's so greasy, she squeezes Crisco from her hair to bake cookies.

Yo mama's so greasy, she uses bacon as a band aid.

Yo mama's so greasy, when she slid into second she ended in Detroit.

Yo mama's so greasy, Texaco buys oil from her.

Yo mama's so greasy, I buttered my popcorn with her leg hairs.

Yo mama's so greasy, her freckles slipped off.