For me it's Spacehunter: Adventures in the Forbidden Zone. Really, it's serious cheese. One of my favorite things is trying to work out who is taking it seriously and who isn't. It's a killer cast, Molly Ringwald as an alien planet valley girl, really, she's deeply funny, Ernie Hudson walking through the same part that he seemed to play in every 80s movie he was in and Michael Ironside as the heavily made up villain, having more fun than the rest of the cast put together.
If you want to come over to my place, I'll make the popcorn and throw it up on the big screen.