Yo mama so stupid she climbed over a glass wall to see what's on the other side.

Yo mama so stupid she tried to drown a fish.

Yo mama so hairy when she looked in the mirror she rang the police and said 

I found bigfoot.       ( I made this one up )

Yo mama so nasty she has to creep up on bathwater.

Yo mama so stupid she got locked in a mattress store and slept on the floor

Yo mama so stupid she tried to put her m&ms in alphabetical order.

You so skinny when I give you a Seamus I get a paper cut.      ( also I made this one up )