sounds like Slaugher High to me (1986) a.k.a. April Fools Day!!
http://www.imdb.com/title/tt0091969/
Slaughter High has Marty. This film has Melvin.
quote:
A group of popular students play a cruel prank on a shy nerd resulting in a terrible accident. Years later a reunion is held where each of the students face a stalker killer who may be the same nerd out for revenge.