Sometimes it’s hard for a child to know where to draw the line in acceptable, fun teasing, and unacceptable teasing. We’re working on this from both directions with both our older children (how to stop unwanted teasing, and how to know when to stop teasing).
It doesn’t help that screaming is so effective at getting attention, and so fun to hear.
I found a storybook at the library that illustrates these concepts without being preachy. It’s well written, and I might even buy it: What a Hat by Holly Keller. Remember the third person trick? I might be overdoing it, but we’ve been talking a lot about Henry, Wizzie, and Newton.