The most obvious: stay away from movies like The 40 Year Old Virgin, American Pie, 50 Shades, anything that has a lot of sex or where sex is the focus of the film. I do not wanna see Jason Biggs fuck a pie or hear Steve Carell describe what his virginal mind thinks a boob feels like while I try and scoot farther away from my parents' bodies.
Chances are you have already seen this movie a number of times, and every time you get a little more exclusive commentary on how much your parents like it. It's cool at first; you get to learn about your parents and their favorite movie, but after a while it's like, "Yeah, ok, I get it, you guys like Robert Redford. Yeah, I also saw him in All The President's Men. He was good there too."
There is a good chance your parents will not feel the same about the film, in which case you may be constantly defending it. If there is a joke or character your parents don't like in it, they will probably vocalize their feelings and then you find yourself defending why the "stink palm" in Mallrats is actually a good joke and a sign of the friendship between the two characters, and crucial to the audience understanding the characters. Mallrats rules.