I am naturally a very conserved and patient person. I think this is sometimes confusing to a 4 year-old, who can easily tell when his mother is unhappy with him due to her tone of voice. For me, I may tell him to stop (or else, etc.), in a matter-of-fact tone of voice, which generally doesn't do anything unless he is pre-inclined to agree.
The time when it is most annoying is when I don't think the action itself requires disciplinary action. It is just annoying me. Like constantly buzzing his lips and blowing raspberries. Apparently, he can enjoy doing it for long periods of time, and really if he's having fun with it, should I care? Usually I might ask him to stop, but then just let it go, because I don't want to put him in time-out for it.
Meanwhile, his mother can just say his name in a warning tone of voice and he'll stop. It's worth mentioning that he is not as familiar with me. We've known and been around each other pretty often for almost 6 months.
Should I make more effort to say my words in a different tone of voice? Should I be more harsh, and start using time-outs even though his choice of fun is just annoying me a bit? Or do I just continue as I have been, and rely on the fact that eventually we'll better understand each other and he'll grow out of it?