Need help with a movie that out in late 80's early 90's, I was just a kid and my memory is really fuzzy. I think the main character is a teenage guy, I think his family might have been taken over by aliens. I remember one scene where the sister is in the shower and her head is on backwards, and then another with the dad being a "butt head" where his head is on his butt.
This sounds like "Meet The Hollowheads", a.k.a. "Life On The Edge".
Link here:
www.imdb.com/title/tt0095608