ПОД ЗАД кому highly coll , rude

VP or PrepP (used as predic) subj: human to reject s.o. , throw s.o. out rudely

X дал Y-y коленкой под зад = X kicked (booted) Y ( Y's butt, Y's ass) out (of place Z)

X threw Y out on Y's ear (ass) (in limited contexts) X gave Y the bumfe rush.