Gallimurphy is a planet in the constellation of Kasterborous and home to the Doctor and the Time Lords, an ancient alien race of sexual predators. Pronounced "Galifree" if you're an alcoholic like Tom Baker.
In the early days, the Time Lords were created by a Holy Trinity. Rassilon, Omega and The Other (Go the fuck to bed, Cartmel) were the three key players here. Rassilon invented table manners, Omega invented the steam powered engine, and The Other discovered ambiguity.
At some point in their history, the Time Lords were a part of the early wars between the First Empires. They abducted children from the other races from various points in their history and stranded them on Gallifrey in the Sex Zone.
The Doctor's Exile
The Doctor was an important Timelord. After having been diddled as a child by Lord President Savile (the Timelords had run out of prisoners of war from the early years), the Doctor was a traumatized child. He spent his early childhood with another victim, The Mattress (this title was given to him in the Academy as his professors enjoyed sleeping on him).
The children had no real power outside of their social circles, so they fought fiercely. The Doctor and the Mattress were targeted by peers and bullied relentlessly. One child was such a huge insufferable cunt that the Doctor bashed him to death with a rock (his weapon of choice, see Za). The Doctor was driven to complete insanity by this act. Being the dick that he was, he transferred the effects of that event on his mind to his best friend after Death offered it to him. Also, Master is still canon no matter what you fucks say!
The Doctor was aged hundreds of years as punishment for this crime and was going to be executed for killing a precious sex slave. The old man managed to escape and bring his granddaughter with him when he met Timelady Pancakes who advised him to steal a different TARDIS. The Doctor escaped and his house was firebombed by Lord Savile.
The Time War
The Timelords are notoriously lazy and rely on their advanced technology to get them everywhere. When it comes to getting their hands dirty, the Timelords lose every time despite their great intellect and physical strength. Being the ABSOLUTE GENIUSES they are, they sent a pacifist (The Doctor) to Skaro to abort the Daleks and commit genocide. Since the Timelords are lazy, they never sent a followup mission after the Doctor only partially succeeded. The Timelords later made the Doctor Lord President, then kicked him out and then put him on trial.
The 7th Doctor took the Hand of Omega when he escaped Gallifrey the first time. Savile had used it to beat him and molest him. Each time the gauntlet plunged into his anus, he shrieked in pain as the force of a supernova being counteracted at all times by a black hole caused havoc on the temporal composition of his ass. He was fisted, regardless of the potential consequences on the time-space continuum. The Hand was used by the Doctor to destroy Skaro and Davros's ship.
The seeds of the Time War were planted. In time, after the Daleks had rebuilt, they launched an attack on the Timelords (probably after half a dozen more occassions of Timelords provoking the Daleks). Billions died all across the universe in response to the opening attack. Eventually every moment in time and space was burning, and trillions were dead. The lazy ass Timelords could barely slow the Daleks down. The war ended when the Doctor killed them both and then went back and changed it so he did not. The Day of the Doctor is canon you plebs.
Gallifrey is now trapped in a hot pocket with the Doctor looking for it. The Doctor remembers his days at the Academy fondly and wants to say hello to Savile.
When will it come back?
When the show-runner wants a cheap way to increase ratings.
Gallifrey is in Ireland! Human Nature. No, despite this, I remember seeing it on a map of Ireland... I've been Mandelaeffect-cucked away! Help!