Your hobby can be anything. For me, it's dancing. For other people, it might be video games. Take your pick. There are a lot of cool things to do out there in the world. Go out there and explore, meet people.
For example, Polaris is a YouTube network of people who generally like to play video games: https://www.youtube.com/user/Polaris. It's a bunch of friends (and business partners) who all share a love of video games and games in general. So even something like video games can be a vehicle for making friends (and meeting girls), if that's your thing.