oh and also one of my friends did this (was previously mentioned too!)
Him and his girl both were big skiers, she liked to ski park to some extent but nothing more than a couple boxes and rails here and there. Anyways, he gouged the words "Prom?" into the bottom of his ski, refilled them with blue p-tex (he had black bases), so that underneath his ski were the words. He then made an edit of the both of them, and at the very end after landing a cork 7 tail he stops at the bottom of the run, takes of the ski and brings the bottom up to the camera.
Just for laughs he also put a clip of him doing a rodeo in slow-mo after the end of the video and you could see the "Prom?" carving while he was in mid-air hahah