Coke planted a wallet with the equivalent of $200 and a much-coveted ticket to a big soccer match on the walkway in the middle of a mall in Portugal. They filmed what happened.
95% of the people who picked up the wallet turned it in to the nearby soccer store.
The crowd of shoppers cheered. The honest citizen was given a Coke (of course). And a ticket to the soccer match, where they were seated with the other wallet-returners. During the match, Coke ran the hidden-camera film of all the wallets being returned on the big screen, then panned to the section of the stadium where these honest citizens were seated. Huge cheers from the crowd.
Most people are honest. Most people like to help others. Most people do ordinary things to build up society.