Arm Tap

I have a friend who, when you're at the movies and something funny happens on screen, he laughs and then he looks at you, to see if you're laughing. Which is one of those things that when you notice it, you can't unnotice it. I also have a friend – I think we've all got one of these – who kind of taps you on the arm when he talks -- a version of saying, Hey, Hey, listen to me – even if it's obvious that you are listening to him...