From his point of view he is probably wanting to show you off and make his friends envious.
He obviously feels comfortable with you, because there is a risk involved, after all you could get drunk, start crying, strip tease, try and get off with his pals, or just tell everyone!
If you have a nice new dress and he is good company, just go and have a nice time, no one is saying you have to talk to his mates.
Gold diggers, well who cares about their opinions!
I'm curious to know what you decide though, so keep us informed!
ps I do agree though, if you REALLY dont want to do it, then DON'T xxxxxx