Breaking water fast

Breaking a fast with alcoholic drink?
I'll be on day 18 when there will be the party of my life. Its a huge drum and bass "concert", my question is, what's gonna happen if I drink a liiittle bit of vodka (just enough to feel it and you know..) with non-sugar 100% lemon juice and water, and the next day I would continue my fast like nothing happened. how would it affect my fast? Will I be in ketosis the next day?