Or just say "I've never seen that, what is it about?"

There's no way you're going to know any reference, just ask, there you go you started a conversation.

You'll get weird looks if you haven't seen the common ones like Star Wars (especially in geek circles), The Matrix, Jurassic Park, the Batman movies, etc.

I haven't seen Star Wars, in fact, it's so fascinating to people it almost always starts a conversation.

If people are not talking to you because you haven't seen star wars I hate to say they are either not worth your time or your breath smells bad!

>it's so fascinating to people it almost always starts a conversation

This is very true, but the outcome is usually negative and alienating to the subject of the discussion (me).