My dad said that this was pretty *beep* up

There are many layers of social commentary within this movie. Taken at face value as a cartoon, I can understand how someone would perceive this to simply be a juvenile cartoon with no underlying motifs or themes. However, you just need to be in the correct frame of mind and understand what crumb and the creaters were trying saterize and display for the mainstream movie goers at the time.

This movie is a historical landmark of cinema IMO.

top 5 favorite movies: 1.The Holy Mountain 2.Gozu 3.Rabbits 4.Irréversible 5.Samurai Rebellion

You really need to see it for yourself, at least once, you'll either instantly love it or hate it.
I loved it, but I like some crazy stuff.

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it IS pretty crazy, but intended to be so. Also, it's over 30 years old... which means that if you're not up on American cultural history of the early 1970s, with focus on the "underground" and whatnot, then you might just miss a lot of what the film is about. If you dig post-hippie radicalism, like confrontational films, and appreciate (even slightly) R. Crumb's work and Ralph Bakshi's other (equally great) films.