Snapping one's fingers in place of the words "That's what she said." Generally used when actually saying "That's what she said" would be inappropriate, such as when at one's mother's house, at work, or at a funeral.
dude 1: "Hey boss, this guy is looking for some work, think we could help him out?"
boss: "Sure, I have two positions to fill, why not use him?
dude 2: *snap*
dude 1: *fist bump*