A sneak technique

For now, my favorite "sneak technique" is the eighth leg-lock: ashi kannuki. In a slightly inferior position, on the bottom of what the BJJ-ers call the half-guard, ashi kannuki allows you to quickly whack a painful leg-lock on your opponent by forming a figure-four using only your legs. It's sneaky because it occurs out of sight, a kind of attack from behind. If your opponent is unfamiliar with ashi kannuki, the chances of success are further increased: (s)he probably won't be able to make sense of what's going on back there -- until it's too late.

Comparing my own execution against the official description (online here, just scroll down the page) from "My Method of Judo", I prefer a variation with my legs reversed -- but it still works nicely.

After introducing this technique to my class last week, along with a couple of other of the safer leg-locks, it was gratifying to see credible attempts being made during the end-of-class randori.

Do you have a favorite "sneak technique"?