I'm sure it'll end up being put to good use before the night is over. After all, you didn't even drink that much compared to everyone else there. It's only fair to give them a chance to avoid ending up sick in the morning too.

[Okay, so it's gonna take a lot more than one half-finished glass of water to ward off the hangovers of all of the patrons still back at the bar, but details. That isn't their problem right now.]