DOESN'T KNOW HIS ASS FROM A HOLE IN THE GROUND
найдено в "Dictionary of American idioms"
doesn't know his ass from a hole in the ground: translationdoesn't know his ass from a hole in the ground & doesn't know his ass from his elbowdoesn't know anything; acts ignorant. (Useass
with caution. Also withdon't
.Don't
used with all persons is folksy.) •That teacher doesn't know his ass from a hole in the ground.
•She's supposed to be an expert, but she doesn't know her ass from her elbow.