Should I be pleased or offended?

A mommy of one of C's playgroup friends called me up asking if we were interested in going out to dinner with her and her husband. You see, they were looking for a couple to join them in a night of beer- swilling and pizza, and we were the only folks they could think of that they could invite out for such an occasion.

I think I am choosing to be pleased. There is nothing wrong with being a beer-swilling, pizza-eating type of friend. Even if I hate beer with a passion. Do you think I actually have to swill the beer, or can I sip a wine while others swill?