Once I observed a co-worker turn the water taps on and off after taking a piss, but he didn't get his hand wet.
Another time I saw a quarter in the urinal, and when I went back, it was gone. The men's washroom was within sight of the reception desk, so I put a dime in the urinal, and asked the receptionist to call me after whenever anyone came out of the washroom, and I'd check to see if the dime was gone.
On a similar note, John Madden told this story when he was the host of Saturday Night Live, (season 7, episode 10, January 30, 1982):
Ted "The Mad Stork" Hendricks was combing his hair above the toilet when he accidentally dropped 35 cents into the toilet bowl. Ted stared at the money, and as Madden put hit, 'his eyes looked like the elevator didn't go all the way to the top floor'.
Hendricks reached into his pocket andpulled out a wad of bills. He then he took a fifty dollar bill, crumpled it up, and threw it in the toilet. When Madden asked him why he did that, Ted said "You don't think I'm sticking my hand in there for thirty-five cents, do you?".