Pi-Pi is the owner of Pi Pi's Splashtown in the episode "Pee". He initially shows absolutely no concern about the amount of urine in his waterpark and, in fact, seems almost unaffected by urine altogether. He claims that the canals of Venice are mostly composed of urine and since he grew up in it with no ill effects, urine must be harmless. So when the scientists tell him to close down his waterpark, he refuses.
When the park is flooded by pee, he is washed away. He later appears on the mountain-like structure that the boys are trapped on, showing remorse for ignoring the scientists' pleas. He tells them about the release valve, submerged below the pee. He states that he cannot reach it because he cannot swim, despite the fact he runs a waterpark, and that he told the scientists that he learned how to swim in Venice a few scenes ago. He makes Kyle agree to swim to the valve, and then claims he needs to drink pee in order to stabilize the water pressure so he doesn't get the bends. He makes Kyle drink an entire glass of pee, but before they can begin the mission, the rescue helicopters arrive. He is not seen after this scene, or in any episodes since, but does appear in the title card in Season Fourteen's opening credits.
He is a short, dark-haired, mustachioed man from Venice, Italy. He usually speaks of himself in the third person and seems to have the overall appearance of a standard Italian stereotype.