I hum different video game tunes randomly. List usually includes Tetris, Dr Mario, Zelda, Katamari, Metal Gear.
Also I can name pretty much any species from all the Star Wars films. Yeah that one in the background there, I know it.
And there are talks about the different academic majors being geeky etc, well I think English Lit majors are way high up there on that list. I'm an English major with a writing minor and pretty much every person in my writing classes are fanatical about something. I've heard debates after classes about practically every TV series, comic, movie, etc that you can think of, and been involved in most of them. We've been asked to leave classrooms because our after class discussions ran on too long and the next lectures were starting. Haha, good times.
Oh and also to add proof to the English being the geekiest major, what other academic discipline has discussions about Klingons in class? This wasn't a film analysis class. This was my poetry class, and my TA started the discussion. What was it about? How the clans in Beowulf were the inspiration for Klingons.