It's wrong to try and ruin someone else good time.
Jim's neighbor is holding a big party, and he suspects there is underage drinking going on.
Jim has to decide whether to call the police.
Jim decides to leave the kids alone and let them be.
Jim calls the police and alerts them there are kids drinking at a party near him.
The kids continue to have a lot of fun and don't have to worry about anything.
The kids at the party fear being arrested, and they can't have fun anymore.