Naff Off
It's like a friendly slap in the face. You use it when someone says something rude but funny about you. It's like saying, 'You're not that great, so just shut up.'
'Naff off, I'm still better than you,' my brother said after I beat him at video games.
'Naff off, I'm not that bad,' my teacher said when I called her out for being late.
My friend said, 'Naff off, I’m still cool,' when I told her she had bad hair.