Let's Analyze Me

For starters, let me say that I'm actually a decent person, a thoughtful and playful male and I get along great with people. The problem? I'm weird in social groups, I don't ever know what to say or how to contribute to conversation, but (lets say) all the sudden we got attacked by a mob of hicks with pitchforks, I would be in the action and all for it.... So why can't I be normal in a group of people standing around making jokes and screwing around? What is preventing me from conversing with the people I like to hang around? (I didn't mean for that to rhyme )Now, before you offer your insight just get in mind that I'm basically like the typical capricorn (I'm using astrology for analogy sake) and if I was in a party (like that commercial) I would be the one standing with my drink, in appropriate conservative clothing sipping on my rum and coke while talking to a hot girl I'd love to take home (and she wants the same, but is wating for me to say the right thing so she can say her thing and then we can go home together) but for some stupid reason I can't bear to do the expected boring thing and lower myself to needless convention, consequently, I go home alone. But what do I do??

Thank you all for helping me out in whatever way you know how. To be clear, I'm not some sociopath or recluse but I do feel a certain sense of disengagement when it comes to relating to people at a party. I find the best antidote is alcohol (to a certain extent) and then I usually can let go a little.I think one of the main problems is I can't let go of the necessary inhibitions so I may have a few strong drinks, and then too many inhibitions are gone. I need to find that happy medium. But, I just wish I could do that without the need of alcohol.The trick too (like many have pointed out) is conversation. I'm all for a good conversation but I find no one is interested in the things I like (general science, scientific issues, life, people, the mind, travel). At least in the parties I go to.So, I'll take everyone's advice the best I can and I'll update later. I don't have a computer until the 8th.Thanks everyone. Let's give it a shot!