expression
stop messing around!; get real!; screw you!
Strong, colloquial imperative used to tell someone to stop joking, being unreasonable, or acting foolishly. Can be confrontational or dismissive depending on tone.
ふざけんな！そんなこと許されると思ってるのか？
Stop screwing around! Do you think that's acceptable?
ふざけんなよ、冗談はやめてくれ。
Get real, man. Quit joking around.