From Longman Dictionary of Contemporary Englishslap somebody down phrasal verb British EnglishCRITICIZEto rudely tell someone that their suggestions, questions, ideas etc are stupid → slap→ See Verb table
Examples from the Corpus
slap down• She even tried denying knowing what I was talking about, but I slapped her down.• She wants to prove him wrong so she can slap me down.• Mr Cheney promptly slapped him down for speaking out of turn, which had more to do with Pentagon power play than strategy.• Better than being big-headed, the thing Uncle Max was always slapping me down for.• Bernard would lie awake for hours waging his nightly battle with carnality, slapping it down, groaning.• He slapped a stone down, in the corner nearest him on the right.• Again he slapped his hand down on the book.• Beyond the door, Mother Bombie's feet in soft felt slippers could be heard slapping angrily down the stairs. 