@mcmoots I do that almost constantly. The lady would have blown a fuse with me nearby. A friend nearly disowned me after a visit to the art museum. (I only set off three proximity alarms, wtf?)
Me, in class: <tapping my eraser on my notes>
Guy: Would you stop that tapping.
Me: You're lucky I don't have my clicky pen today.
Guy: I *KNOW*.
People keep telling me about fidget toys. I should probably look into it. (I've been diagnosed with adhd, for what it's worth.)