n'ombre
A crazy, loud way to say you think someone is lying. Like when someone says they're the best at something and you yell 'N'ombre!' because they're not.
She said she's the best at math. I said, 'N'ombre? I got a better grade than you.'
He said he can eat a whole pizza. I said, 'N'ombre? I saw you struggle with half.'
She said she can dance like a pro. I said, 'N'ombre? You can't even stand still.'