I'm going to tell a stranger his wife has a boyfriend
Why would you tell a stranger such a thing?
I just wanted to have a little fun at his expense.
If you aren't sure that someone's wife is being unfaithful, you shouldn't plant a seed of doubt in their minds. You may end up destroying their relationships despite it not being true.
Isn't that my business? I don't see how my actions are hurting anyone.
Rumors are very hurtful and not something you should find entertainment in. Rumors can damage people's lives and relationships.