When a guy and girl are sexually intimate, the practice of the guy to alternate between bottom and top holes (anus and vagina). No particular pattern of action is required, and the switch-off can be completely random (ie: top, top, bottom, top, bottom, top, bottom, bottom, bottom, top, fist).
Create special patterns to signify festive or celebratory events and occassions; re-live these occassions through fantastic, nostalgic sexual practices!
Donnie: Tim was derfing Julie and covered her vagina with shit.
Darcy: Goddam! O_O