When you are fingering a girl, and a rogue finger accidentally hooks into the anus. Although this incident is generally accidental, it is possible to fake it for personal gain. Occationally said girl won't even notice, if you correct yourself quickly enough.
"Man, me and Alice were going at it the other night, and I accidentally pulled the old 'Swirl'n Sneak'. She didn't even notice!"
by Luke Stevens June 20, 2007