Like Ali says, it's like joining a party where everyone else already knows each other. It sucks, but then there is the option to get to know them and become part of the crowd, unlike if you attend a party at a conference where everyone is a stranger.
But in such a situation, if you wanted to make friends, you wouldn't barge right in, criticising the way they arrange their furniture, deciding to keep your shoes on because that's what you do at home, and demanding that everyone wash off their perfume because you don't like it and explains their jokes to you because you don't get it. Well not if you wanted to make friends and be invited back, anyway.
There are few rules here, but this is essentially one of them. Almost everyone was a newb at some point, and there are a great variety of old hands here, so clearly it is possible even if you are an absolute dickhole like ... %^#*$^, &$%# &$^@$*, and ^$*%^^#*&#. or totally awesome like me.
