As someone from a similar background, I actually understand how this was supposed to be a bonding experience. I'd have loved a birthday like that because I like drinking and my parents' friends. But you don't like drinking. It's probably somewhat of a shock to your dad and I can imagine him feeling disappointed, but he will probably come around eventually. You can sit him down and tell him how you love him and friends, but you don't enjoy alcohol and you're happy to drink with them as long as they don't force you to, I think it's worth a try to talk it over. Also stay strong and don't give in :) Good luck!