Poison. You have approximately 48 hours left to find the cure.
Don't quite know why people here think it would be rude to ask what the drink is. At the end of the day, they've given you a drink you didn't order without any warning, or even telling you what it is. It's not rude at all to ask what it is. If you go all "what the hell is this you just gave me" kind of tone to them, then yeah, that'd be rude, but asking politely what drink they just put on your table expecting you to have is not even slightly rude - it's expected as you'd have to be a bit of a fool to drink something without even knowing what it is.
TL;DR. Not rude to ask what it is. It's only rude if you ask in a rude way.