@TheDewd: Honestly? People don't need excuses not to hang out with people outside of work. Camaraderie can be helpful for office morale, and I have no problem engaging folks in polite conversation and watercooler talk. But that's generally where I keep my work relationships, mostly because I can't really relate to the average person in the offices I've worked in. Like I worked in a call center one time with a bunch of 19 year olds that only ever talked about various Kardashians, and were constantly expressing bafflement at the fact that I was a 20-something woman without kids and babydaddy drama. I wasn't trying to get involved with people like that. Then there was the office full of conservative Christians. I can get along just fine with people who have different beliefs and worldviews from me, but I'm not exactly chomping at the bit to spend my free time with people who constantly try to convert me to their religion because they think I'm too nice to go to hell (direct quote).

I can count the number of friends I've made and kept from work on one hand. In those cases, they were people I probably would have made friends with had we met anywhere else, because we had things in common besides work (queerness, similar politics, shared interest in fandom or geek culture, etc).