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.
This phrase is used to describe something very modern or updated or something that no longer looks like what it's used to.
It has been a long time since I left my high school, and now I have to admit that it's certainly not your father's high school anymore.