Sneaking a thumb into a womens private area. Traditionally done to strippers and cheerleaders, but can also be used against any woman wearing a short skirt and little to no panties.

stripper fingering ass-whipping A daring maneuver performed by only the drunkest (or dumbest) of strip club goers, the magic thumb is when you slip your thumb into a woman's down-stairs mix-up, typically unapproved and almost always uncalled for.