godan verb (-su), transitive verb
slap down; knock down; floor
To strike someone with an open hand or a slap hard enough to knock them down. Conveys a forceful, often sudden action.
彼は相手を張り倒した。
He slapped his opponent down.
あんな失礼なことを言ったら
If you say something that rude, you'll get slapped down.