A Maderno Fountain.

Noun: An act in which a man or a woman kneels down and then tilts their head to have their open mouth toward the ceiling. Another person then straddles the kneeling person(the fountain)'s face, so that their anus is atop the fountain's forehead and their genitals facing towards the fountain's mouth.

The person is then to begin urination into the fountain's mouth, at which point the fountain begins the gargle the urine. The person is then to push a small amount of fecal matter from their anus onto the fountain's forehead and then draw a cross shape on the fountains forehead, reminiscent of drawing a cross on someone's forehead on Ash Tuesday, hence the name 'A Maderno Fountain', as the Maderno Fountain is a fountain in Saint Peter's square.

"Mate he's a proper creepy cunt, he probably gets off to people making him into A Maderno Fountain."