When you are in the act of coitus and a guy or girl (because it could go both way) sticks their hand into the girls' vagina for the pleasure of the girl. Similar to fingering
1. Sebastian "Dudeee, last night I was with this fox and I stuck my hand in the cookie jar" ;)
2. Bianca "Hey girlyyyy, last night I was with this HOTTT guy and he stuck his hand in the cookie jar!"
A game involving a Matt Jacker and several of your friends.
the aim is to get further away than your friends from the Matt Jack whilst giving clues to the Matt Jacker that you are getting away