she has a kink in her slinky.
- Or...Couple sandwiches short of a picnic
Thats gonna go over like a turd in the punch bowl
we seem to have some of the same words with different applicationsnot the sharpest...
... pencil in the pack
... tool in the shed

Lot's of permutations on this one!!!we seem to have some of the same words with different applications
sharp as a bowling ball
That is one of my favorites and I forgot it!!! 

A closed mouth gathers no feet

So ugly that when you was born the doctor slapped yo mamaSo ugly yo momma had to tie a pork chop around your neck to get the dog to play with you.