+1 for wristlocks. One of our black belts is partial to a neck crack he calls "who's your Daddy"... That one's tricky to explain, and it's a gi only sub.

Tea bag Kimura!

Wrist locks. Especially when they are being lazy with their grips. I have one when people grab my lapel with a weak grip and there was a good 2 weeks where I would tap most people right when they engage during a roll. Technically legal but dirty, totally unfair, and taking the fun out of a good roll.

Maybe I should bring it back....