A toilet was a device used for the disposal of bodily wastes.
Blon Fel-Fotch Passameer-Day Slitheen, in the form of Margaret Blaine, took Cathy Salt to the toilets in order to kill her, after claiming her "little tummy" was "complaining" when she farted loudly. Soon after, when she farted after entering the toilet, Cathy remarked, "Sounds like we got here just in time.". When Cathy revealed she was pregnant in their talk, Margaret decided to let her go. (DW: Boom Town)
There were no toilets in the base of LINDA, requiring members to use a pub, as Victor Kennedy was reminded when he claimed Mr Skinner gone there. In reality Victor had absorbed Skinner and was trying to get rid of Elton and Ursula. (DW: Love & Monsters)
Both Penny Carter and Donna Noble hid in a toilet cubicle for a day, while investigating Adipose Industries. Miss Foster soon discovered someone was spying on her and searched the toilets. She found Penny, but not Donna. (DW: Partners in Crime)
Amy Pond went to ladies' toilets of the White House in 1969 because she wasn't feeling well. She discovered a Silent there, and saw it destroy a woman called Joy. (DW: The Impossible Astronaut)