I'm a parodist and I think this is OK.

545, I never saw the movie, but I think this is pretty good.

The original song was so brilliant, it is almost sacrilege to parody it. Inevitably, your song suffers by comparison. Much better to choose a straight song, maybe something like "Bill" or "I'm So Pretty" or one of the early Beatles ballads. Put funny lyrics to a sentimental or serious tune, and the contrast makes it funnier. Do you see? This is a good effort, but needs work. For instance, many of your verses don't rhyme. Coupling "weaponry" and "Heeeere's Johnny" is good, although putting the emphasis on the second syllable of Johnny is a bit awkward. But "Keith Richards" and "madman"? "Chain saw" and "killer"? How about this: I smoke and drink, I drool and leer, I love to run amuck. I look just like Keith Richards And sound like Donald Duck. Awkward phrasing like "with me I have a chainsaw" do nothing for this song. How about: I'm really strange, I'm so deranged, I sleep with my chainsaw. And if you look beneath my bed... You'll find what's left of Ma. Do you see how tight that verse is, compared with the original? Also, much funnier. Don't mind me, I have this thing about grammar and rhymes and lines scanning. I think my mother was frightened by a thesaurus while I was in the womb. Anyway, I'm sure your Dad loved it. Keep writing. You are welcome to use my suggestions.

What Wordsmith said.

*Raises hand* Awesome, this parody.

Well it's funny because it's true and a song doesn't have to ryme to be a song.

Your mum is afraid of a thesaurus? (Laughs hysterically)