not know one's arse from one's elbow
01
to show a great lack of intelligence or poor judgment
Dialect
British
British
![{not} [know] {one's} arse from {one's} elbow definition and meaning](https://cdn.langeek.co/photo/44844/original/?type=jpeg "{not} [know] {one's} arse from {one's} elbow definition and meaning")
例
Do n't take his word for it — he does n't know his arse from his elbow.
to show a great lack of intelligence or poor judgment
British
