I had a friend (who is my age) who had never seen the original Star Wars trilogy or the Indiana Jones trilogy until me and a few other friends forced him to watch them all; he was 22. He was quite deprived, it was depressing. It's not necessarily nerdy (only if you spend your life watching it over and over and doing all the cosplay and playing all the games and reading all the books all the time), but it's a definitive part of pop-culture.
I told him that after he saw those original Star Wars movies, especially Empire Strikes Back, it'd be like an enlightenment, and he'd suddenly understand so many jokes and references that have been made ever since then. He said that's what he experienced, and it was hilarious.