When I was a kid we had a very popular entertainment. We picked up old wallets, took a dump inside, threw it out on the plain sight and then we were sitting in a well-hidden place nearby where we were watching some poor man/woman get his/hers hands dirty with shit while checking the contents of the wallet.
We thought it was the pinnacle of humour and we thought we were superior in intelligence to the victims of our pranks. It wasn't until I got older that I realised that the reason this prank worked was because people just didn't think there was such a stupid person who would take a dump in a wallet.