Definitions by Graham Rayburn

Nantucket Ninja 

If you're fucking your woman from behind, right as you're about to cum you karate chop the back of her neck to render her unconscious and thereby causing a contraction of her vagina which adds to your pleasure. The key to yell "Hiya!" right at the point you administer the karate chop.

Dude, I gave your sister the Nantucket Ninja last night and not only did I have the best orgasm of my life, but she doesn't remember a thing!

Nantucket Ninja by Graham Rayburn February 16, 2008