n'ombre
A loud, shocking way to say you think someone is full of crap. Like when someone says they're the best and you say 'N'ombre!' because they're not.
He said he's the best at video games. I said, 'N'ombre? I beat you in 10 seconds.'
She said she's the best at drawing. I said, 'N'ombre? Your drawing looks like a cat hit it.'
He said he can run a marathon. I said, 'N'ombre? You can't even run a block.'