can't tell (one's) arse from (one's) elbow(redirected from can't tell my arse from my elbow)
?Note: This page may contain content that is offensive or inappropriate for some readers.
can't tell (one's) arse from (one's) elbow
rude slang Is very stupid or dimwitted. I'm not surprised to hear that she got lost two blocks away from her house—she's can't tell her arse from her elbow.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.