This is definitely the best of the 4 "Ghoulies" movies, by a wide margin. The other ones just aren't nearly entertaining enough, although they are stupid.
Just to give an example of the type of humor here, there's one scene where the professor (Kevin McCarthy) says something like "If you do not quit these moronic pranks, the axe will fall", then cuts to a scene where they're chopping up a pizza with an axe at a frat party and drinking tons of beer. Great!
Another scene that comes to mind is where the Ghoulies break into the kitchen of the frat house, open the refrigerator, stare at the awe of the 2000 cans of beer, and proceed to topple the stack and get buried. Of course they "drink" their way out of the pile.