I lucked out big time with my first roommate. First time we met was in our dorm room on move-in day, I knew his name ahead of time but we never even talked or anything up until then.
His two best friends from college were literally next door to us, so the three of them were always together and I sometimes tagged along, but based on what little I knew about them I didn't feel like we had much in common, though my roommate is still the most laid back person I've ever met in my life and we got along fine. I remember the exact moment when I first felt like part of their group. About a week after we moved in we all went for lunch together and they spent a fair amount of the time talking about their mutual friends, shit that I couldn't really contribute to, until there was a lull in the conversation and one of his friends, who has a really offbeat sense of humor, says "So yeah, I was balls deep in a 9 year old when his dad walked in"
so while they're laughing, I immediately looked at him and say "no, no, it's 'so I was balls deep in a 9 year old when my clown nose fell off'" and I haven't seen them laugh at anything that hard since then. Instant best friends, up until I transferred schools the next semester, we still make an effort to hang out every few months.
Fuck, now I miss those guys. Anyway, good luck, it's a hell of a lot of fun.