It is a trend to promote a horror movie with a prankvertising (a commercial based by prank). It is easy and if it is well done it has viral potential, so less budget needed for the media buying.
Paramount Pictures did a prankvertising directed by Gregory Plotkin. The spot promotes Paranormal Activity: The Ghost Dimension and I can say that it is a successful prank.
There were awesome reactions, reactions that make you laugh.