Not know (one's) ass from a hole in the ground slang rude
To be extremely stupid; not to be alert
She didn't know her ass from a hole in the ground when quitting such a decent job.
What! You refused such a good price! You don't know your ass from a hole in the ground.
To have no money
Extremely stupid
Very stupid, or silly
Used to describe someone who is naive, gullible, inexperienced, easily fooled, ignorant, unsophisticated, etc.
To say, or believe something or someone that seems completely crazy, delusional, or stupid
The origin of this slang is not clear.
If someone or something stands/sticks out like a sore thumb, they are so noticeable that the surrounding people and things notice them.
The dress codes of the wedding are blue and green, but Liza wore the red dress - she stuck out like a sore thumb.