It's based on the Madonna song 4 minutes. When 4 minutes is called, everyone within earshot must finish their drink within 4 minutes, regardless of how much alcohol is left in the drink. I've personally called 4 minutes and seen someone finish a Long Island in 2 and a half.
4 Minutes can also be called via text message, IM, or any other form of viable communications.
4 Minutes can be called in situations outside of drinking (sex, etc) but that is not the original usage.
Man 1: F U! I just got this 32 oz miller lite!
Man 2: Man up!
Such a hit can only come from the Queen of Pop herself (along with Prince of Pop, Justin Timberlake)
tick tock tick tock tick tock!