I'd honestly say he was using some sort of illegal substance except that his name was Spaz which seems to link to his mental state rather than something else.
I don't know if the developers really would have wanted to have a drugged out main character either.. but they did have the "afro-sporting caterpillars".

Additionally; it makes for a boring explanation. Arjan and Cliff always enjoy a real solid character description and an amusing one at that. It's too bad there wasn't much of a jazz2 readme, the first one was a great read. We'll never know what Spaz's favorite book is (Any guesses?)