ふざけんなよ

don't screw around!

→ ふざける
phrase Rare #35,170
don't screw around! A rough, angry expression. It is a contracted form of ふざけるなよ and can also mean “you've got to be kidding!” depending on context.
JA: ふざけんなよ、そんな話信じられるか!
EN: Don't screw around—do you really expect me to believe that?

ふざけんなよ帆高!

Cut it out, Hodaka!

— 天気の子 (2019)

おいおい、ふざけんなよ!?

Hey, you've got to be kidding me!

— ミスティック・リバー (2003)

ふざけんなよ

You’ve got to be kidding me.

— ブレット・トレイン (2022)

(田中)ふざけんなよこら

(Tanaka) Don't mess with me, you punk!

— 君の名は。 (2016)

ふざけんなよ!

Don't mess with me!

— ベイビー・ブローカー (2022)