After Midnight (1989)
How did you miss this "classic" from 1989? After Midnight made me laugh so much it annoyed my wife! While the scenes are meant to be scary, their timing, setup or just premise made me laugh. For instance, it opens with a "Professor of Fear" teaching a class in school. He pulls out a revolver and single cartridge, loads the pistol, spins the cylinder and then puts it to the head of the class tough guy. He pulls the trigger, and nothing happens. He then puts it to his own head, pulls the trigger and sprays blood all over the wall. I found myself jumping up yelling "Class dismissed!". But it was all a trick he plays!
And then there's the story of the couple who get conveniently stranded next to an old house, and she goes one way to explore it and he goes another for some odd reason. He finds human skulls and when a door opens there's a guy with giant hedge clippers. The door closes and our hero arms himself with a saber and when the door opens a second time (just after the woman, dressed as the hedge clipper guy, tells her relatives "He'll probably kill me for scaring him like this for his party"), the guy decapitates her! Again, what she said, and the timing and general nonsensical nature made it funny as her head goes flying!
Think Scooby Do with decapitations and that pretty much captures the movie. So, so riff worthy and low hanging fruit. By the way, it has the CSI lady Marg Helgenberger in it.