nahtameen
A Londoner's way of saying 'na meen' to make you feel like a complete numpty. It's like when you're being a bit of a prat and you think you're the most important person in the room.
'You think you're the best at chess? Nahtameen!'
'He kept bragging about his job. Nahtameen!'
'She said she'd win the lottery. Nahtameen!'