That dog won't hunt. (That idea won't work.)
Snipe-hunt. (Wild goose chase.)
Not enough dogs under that porch. (Not smart, or not playing with a full deck (sic).)
Sitting on G waiting on O. (I'm ready.)
Have you got brass-*** or something? (Why are you so slow - military-derived.)
Hotter than a sterno bath. (Can refer to actual heat or the attractiveness of someone.)
Cock the pimp hand. (Prepare to strike a "ho," or anyone who annoys you.)
Pimple on the *** of progress. (Something useless.)
Can't find your *** with both hands. (Refers to stupidity.)
Dumb as a bag of hammers. (See last entry.)
Tango Uniform (Nice way of saying "tits up" which means "dead.")
That is just STUpid. (Inflection of STUpid often refers to something that is "sick," "Awesome," "fly," or otherwise good to a high degree.
Bat-**** crazy. (Could refer to insanity brought on by bat fecal matter, but normally refers to someone who's just plain bonkers.)
Redneck reunion. (Where I'm from in Alabama, I've heard this used to refer to any gathering of rural people, but it is often used to refer to high school proms, especially out in the sticks where many people are related and probably knocking boots (see below).)
Knocking boots. (Having sex.)
Busting caps. (Shooting bullets, as into someone's ***.)