뒤통수를 쳐요 · 뒤통수를 쳤어요 · 뒤통수를 맞다 (be betrayed)
to stab someone in the back; to betray
Example
믿었던 동료가 내 아이디어를 훔쳐서 뒤통수를 쳤어요.
A coworker I trusted stole my idea and stabbed me in the back.
Word parts
Literally 'to hit the back of someone's head,' where they can't see it coming.
Good to know
From the victim's side, say 뒤통수를 맞다.