Drink it means anything in the world. It is usually said when you know you are write and the other person is wrong and you want to confirm this with them. You tell them to "Drink It" because they are a disgrace for being wrong.
Tom: Steve whats 2+2?
Steve: 2+2 is 5
Tom: your so stupid, its 4 Steve... DRINK IT
Steve: Ahh nutsack