Yo momma's so cross-eyed, when she cries, tears roll down her back.
Yo momma so old, she farts dust
Yo momma's breath so funky it smells like Altoids in reverse!
Yo momma so ugly she looked out the window and was arrested for mooning
Yo momma's so fat, if she were one of the three little pigs, she'd say "not by the hairs of my twenty-six chins.