The Velvet Hammer Method
Start with, “Got a minute? Great. I need your help.”
It should be said in a friendly way. It’s a disarming way to get attention sincerely and genuinely. And you do need their help because their behavior is becoming problematic.
Next, say, “I noticed that [problem behavior goes here.] (Pause) I was wondering what’s causing this problem (pause), because it cannot continue. What do you suggest we do?”
Note that the word ‘because’ is one of the 30 most persuasive words. Everyone wants to know what comes after it.