"Zog" was a colloquialism Donna Noble once employed to indicate to the Tenth Doctor that she was referring to a hypothetical planet. (TV: The Unicorn and the Wasp)
There was, however, an actual planet named Zog. Captain Jack Harkness once visited a bar on the planet on New Year's Eve 2066. There, an individual gave him instructions for either the earlier or later version of him. This version, upon opening a box on 7 August 1941, relived these experiences. (COMIC: Overture)
The Ninth Doctor left Rose Tyler talking to some Habrians in the Zaggit Zagoo bar on Zog. (PROSE: The Red Bicycle)
Jack later met Alonso Frame in the Zaggit Zagoo bar on Zog. (TV: The End of Time)