The act of grinding (with or without insertion) on your sleep partner subconsiously, while in a state of unawareness. The occurance can be recalled only vaguely, much like a dream might be. This phenomenon usually occurs when one or both parties goes to sleep horny.
I didn't plan on having sex with Lance that night, but I found myself sleep humping him at about 2 in the morning. Oops.
by Carly Bizzle October 20, 2007