English to French Other Cinema, Film, TV, Drama General

Hello everyone,

I am looking for a translation for the expression ''Naughty dog''. The context: two friends are talking, one of the two fell in love but hides it from his friend. The conversation is :

A: What's the matter with you? You haven't been yourself since yesterday.
A: What, is it a girl?
A: You naughty dog!
A: Who? Do I know her? Tell me.
B: I'll tell you later.

Thank you !!!