whilst having sex with ones girlfriend, wife, or boyfriend i suppose, the screen in a window is removed, and the receiver is hung out the window. the giver then repeatedly slams the window frame down on the penis, resulting in pain and satisfaction at the same time.
Dude 1: hey man, i totally windowpained with megan last night!
Dude 2: wicked! how was it?
Dude 1: o it hurt so good!