Thoughts of April Fools Day remind me of tricks people play on each other. Tricks can be fun, but also can be thoughtless or cruel. Children are especially mean to each other, perhaps because they haven't yet developed layers of sensibilities.
When we grow into adults, we learn more about how to treat people kindly. That doesn't mean we always practice what we learn. I believe most people try. Still, sometimes the child in us comes out and we let slip with something that later we regret saying or doing.
Tricks or pranks that turn vicious, jokes that smart, those can all be used in books, not only when referring to a villain, but also a hero or heroine. Our characters are human. It's okay for them to be flawed, especially if they realize their imperfections and feel regret.
Do you know of any books where a main character did something in jest they later regretted? Or thought they were being funny, but then realized they'd acted or spoken out of spite? Or, maybe you've written such a book or will now. Please share.