expr BrE vulg sl Why do you ask him of all people? He doesn't know his arse from his elbow — Нашел кого спрашивать. Да он, бля, глуп как пробка
NOT KNOW ONE'S ARSE FROM ONE'S ELBOW
Англо-русский перевод NOT KNOW ONE'S ARSE FROM ONE'S ELBOW
Глазунов. New English-Russian dictionary of modern colloquial English Glazunov. Новый Англо-Русский словарь современной разговорной лексики Глазунов. 2003