When an acquaintance initializes a celebratory grab of the buttocks, where the index and middle finger protrude into the wedging of the glutteus maximus.
This is originated by Iranian soccer players, who risked fines and 74 lashes, in order to properly celebrate a goal made by a teammate. The term was coined by Greg Gutfeld.
Karim: "Hey man, get your fingers out of my butt!"
Omar: "haha! looks like you just caught a Charlie Cornheiser!"