I have the "Beware Rock" too, but I don't know what you're looking for concerning the name of this type of laugh. If there's an original source it was taken from, like a movie, I don't know of it. The laugh sounds pretty sinister though.
Vincent Price was well known for his maniacal evil laughter or voice in various roles. He is also the voice over and laughter you here in Michael Jackson's "thriller".
When I hear part of your "rock" laughter it makes me think of his spook talent, and some of it really does sound very much like him.