Tapping on the desk -
I don't cope very well with repetitive noises. So, you can imagine, there are times when I go a bit spare in class. And there is always at least 1 persistent tapper per 10 children. Mostly they are gorgeous about it and will stop when you ask. For the inveterate tappers, my secret weapon is blue tac. Gives the kid something to fidget with and it is silent.
The day a kid in my class can do this is the day I let that kid tap as much as they want.