Grotesque act of social terrorism.
1) Spot someone you have little or no respect for at a social gathering.
2) Sneakily put your hand down the back of your own pants, and have a good rummage, exposing it to (how can I put this..?) ass-sweat.
3) Boldly run up to your target, extending the 'infected' hand for him/her to shake.
4) They are left with a stinky hand and complete ignorance of the insult they have been exposed to. You are left with an equally stinky hand, but also a sense of pride/victory.

Aka Shaolin Stinkpalm

To stick your hand down the crack of your ass and then shake hands with an enemy, hopefully where they will eat with their fingers.

Something retarded comic book fans attempt to do to Kevin Smith at comic conventions.