A parallel existence in which events may unfold differently and particles are antimatter and so forth. A subset of the multiverse.
Amply illustrated in this Youtube conversation.

Dude 1: I shudder to think that there may be an alternate universe out there in which McCain-Palin won the elections! Wait, she could be PRESIDENT in this one!

Dude 2: There is such a universe. In that universe Gore and Lieberman won. Gore was killed by an Iraqi-Iranian-Pakistani Terrorist while he was looking out a window in the Twin Towers. President Lieberman made a tearful speech declaring Gore a martyr. He the declared World War on Islam and bombed Egypt.

The US is also bankrupt in that reality.
by Vamavid November 20, 2009
Having a kick ass orgasm while getting a blumpkin, eating a good sandwich, injecting heroin, watching an awesome film, receiving a nice message and being told you won the lottery.
tom: fred, you look so serene, man, what happened?

fred: (ecstatically) Alternate universe

tom: No....fucking....way!
by bluhluhluhshning April 20, 2010
An alternative universe is a combination of getting a blow job while taking a dump (blumpkin), getting a massage, eating a sandwich, watching a good movie, being on heroin, reading a newspaper, and winning the lottery.
Only a few man in the world ever had an alternative universe, they're so lucky.
by Its That Guy!!! April 7, 2011
Jack: You wanna go to the alternate universe?
Dave: Why?
Jack: Cause that's where all the magic happens.
by vashill April 6, 2020
A chad server with lots of pussy join if you want to get swarmed by pussei
Bob: Hey Billy are you in Breakroom: Alternate Universe?
Billy: Yes, why?
Bob: God, you must be getting swarmed by pussei
Billy: 😎