I BELIEVE the movie you are looking for is Saturday the 14th Strikes Back. It's a comedy (well sorta), about a young teenager whose family moves into this new noise that has a crack in the basement leading to a dimension of monsters (or something, it's been a LONG time since I saw the film.)
It's got vampires, werewolves, and other monsters. The scene you mention I believe the teen is going to school only to find that the evil from his house has spread and is starting to take over other people.
IIRC there are several musical numbers in the film, including one song by a female vampire that goes, "Don't even try it, living on a vampire's diet!"
I do remember one or two scenes that were funny.. for instance, in one seen the teen is confronting the head bad guy in his garage where there's a crack in the floor that's leaking evil in the form of steam. The bad guy has explain who he's going to conquer the world by entering our dimension or some such, and teen (who has a bucket) says, basically, "No, you're not! I'm going to stop you! I've got this special cement, I'm going pour over the crack; it's super strong and NOTHING can break it!"
We turns the bucket upside down, and the cement falls out--hardened into one solid piece.
But other than that, it wasn't really funny.
I am told it's on DVD though...http://imdb.com/title/tt0096039/