a fifty
A fifty is when you mess up and someone smacks you across the back of the head with a hand so hard, it feels like you just got burned by a flaming rug.
He said 'Fifty' and I smacked him so hard he got a rug burn.
She messed up my game, and I gave her a fifty right in front of everyone.
He didn’t say 'No Fifty,' so I got to hit him with my hand.