interjection
liar!; you're lying!; yeah, right!
Colloquial interjection used to call someone a liar or express disbelief, often in a light or teasing tone.
「昨日、有名人に会ったんだ」「嘘つけ！」
"I met a celebrity yesterday." "Liar!"
「宿題やったよ」「嘘つけ、まだやってないでしょ」
"I did my homework." "Yeah, right, you haven't done it yet."
Imperative form of 嘘をつく (to tell a lie), literally 'tell a lie!', used as an interjection.