"Shotgun shack" - house where front and back doors are arranged so that one could shoot a shotgun into the front door and out the back.
"Shotgun a beer" - piercing the side of the a beer can near the bottom, placing mouth over hole whle can in held vertical, then popping the top - make sure to drink it and not wear it.
"Hotter than a two dollar pistol."
"Slap leather"