My grandmother liked "You don't know your ass from a hole in the ground!" A variant is "You don't know your ass from your elbow!" This one really IS elbow, Bert! She also liked "He didn't have a pot to piss in!" My grandmother was a colorful character! Another from that era is "He can't tell s*** from Shinola!" Are there young folks or people from abroad unfamiliar with Shinola? One that I like is "He's so full of s*** his eyes are brown!"