Urine, colloquially referred to as piss or pee, was a liquid expelled from the body as a way of ridding toxins.
Convicted rapist and killer Oswald Danes claimed that guards were putting urine in his food in jail. Although they covered it with things like cream and gravy, he could still taste the urine, for, as he put it, "[piss] has a way of enduring". (TV: The New World)
In 1782, Lisa-Beth Lachlan noticed that the regular customers of the Shakespeare's Head tavern in London often urinated on the floor, leaving wet patches which the posture-girls had to avoid as they struck their obscene poses. Later in the year, at the Manchester tavern The White Hart, a local prostitute lost a potential gentleman customer to Katya after turning her back for two minutes to urinate in a back-alley. (PROSE: The Adventuress of Henrietta Street)
Before meeting the Eighth Doctor, Anji Kapoor and her boyfriend Dave Young visited a statue in Brussels called The Mannikin Pis, which depicted "a naked little boy, happily urinating into the air". (PROSE: Escape Velocity)
In a timeline created by Faction Paradox, Sarah Jane Smith "had to take a pee behind someone's house" in the town of Anathema on the planet Dust. She doubted that anyone there would have cared if they had seen her in the act, and noted that "she'd never had to think about these little biological details on most of the planets she'd been to." (PROSE: Interference: Book One)