The act of creating an optical illusion (usually in a photo) in which a person appears to be beheaded and holding their own head, when in reality there are actually two people in the photo.
The illusion requires two participants. The most common method involves one person laying on their back with their head flopped over the edge of a bed or platform so as to hide it from view, while the other person lays on the other side of the platform in such a manner that everything but their head is out of view. The first person then grabs on to the second person's head, and if done correctly will look like one person is laying down holding their own head.
My friend and I took a horsemaning pic today, check it out it's awesome!