First of all, I'm not the type of guy that goes out a lot, but the times that I did, I noticed this:

Basically, I'd be chatting with some guys on the street, bars or clubs(sometimes I like to talk to strangers to have a conversation even though I'm a bit introverted ), and for whatever reason, there were so often that this guy's friends would come by and say hi to him while we were having a conversation, which is totally cool. But what was strange to me is that they would be starting to talk and joking and whatever, basically completely ignoring my existence there, I'd be standing there and not knowing what to do. If it were me, or when I hang out with my straight friends, me and my friends would usually try to introduce the third person into the conversation and not just ignore that person. It made me feel not so good..as if I don't really matter. Is this normal and I just need to get used to it? Or is it because they just don't give a crap.

A little rant, since it just happened to me where conversation got interrupted 5 or 6 times, and I got to experience that awkwardness 5 or 6 times in a row.