I had my students give impromptu speeches on Saturday, and one of them got up and started clicking a pen in her left hand as she previewed the points she planned to make. I'm trying to get them to drop the nervous habits before they do their exhibition, and being polite about it is not working that well. So I just barked "drop your pen!"
Her eyes got really wide and she stammered, "...Mr. Ryan!" which is what she calls me to be ironic and funny because I am clearly not a Mr. Ryan. Except she seemed genuinely terrified. And then she glanced down at her pants, and I was like, "oh, ack, pen, not pants, drop your pen." It was pretty much traumatic for both of us, but I think everyone else in the class enjoyed that.