Actually, from what my doc told me you should not have any alcohol for about 3 days after your last dose of Flagyl as it takes that long to completely leave your system. If you drink within that time, you run the risk of severe vomiting. I was on Flagyl for 6 months which meant no alcohol for my birthday or New Years Eve! I didn't even bother with a sip of alcohol as from what I've been told, it's just not worth it. Non-stop, violent vomiting just didn't seem like an appealing way of celebrating.
By the way, Flagyl works just like any other antibiotic. It needs to be taken continuously for the prescribed amount of time or it doesn't work. If you miss more than one dose, you may have to start from scratch. Some people are on it for a few weeks while others need to take it for months. Talk to your doc about it.
Sorry to be such a party pooper! I think we all know what it's like to want to be "normal"; especially after a flare up. Only you can decide if it's worth it for you. I hope you are able to have a great weekend regardless of what you end up deciding! :)