A couple of my favorites:

"Felt like a duck at a cock fight"
"I have no dog in that fight" (variation of one above)
"Pretty as a deer, but dumber than owl shit"
"One wheel in the dirt" (meaning about to go out of control)
"Smelled like a fart in a gym sock"
"Shitting in tall cotton" (meaning doing well in life)
"Ugly as a stump"
"I want to date outside the family"
"Too much sugar for the dime" (meaning overwhelming or false praise)
"Herding cats" or "Pushing string" (meaning doing something difficult)