The answer to your conundrum is, I'm afraid, the obvious one. Neck two or three beers rapidly as soon as you arrive. A whisky chaser would not go amiss, either. In this way, within 30 minutes or so the iitial alcohol rush will convince you that you are having the greatest time evs, and you will engage in animated conversation with some boring numpty and absolutely love it.
An hour later you will feel fully pissed and nauseous BUT, so will everyone else, so you can sneak away.