STARDIS
The STARDIS was a teleport vessel based on legends of the Doctor's TARDIS, owned by the con artist Banto Zame who posed as the Doctor with his companion Sally-Anne Stubbins.
It appeared in the shape of an Earth portaloo due to an historical inaccuracy based on the TARDIS's police box exterior. The STARDIS only contained a short range teleportation device and unlike the real TARDIS, the initials didn't appear to stand for anything. The Sixth Doctor and Melanie Bush forced their way inside with Banto and Sally-Anne and materialised inside the real TARDIS. The dematerialisation/rematerialisation sounded like a toilet flushing. (AUDIO: The One Doctor)