This is a phenomena that I’ve recently noticed in these icy, snowy times. You do it before you go in a shop, as you go in the front door, after you’ve crossed a snowy bit on the pavement, or after ploughing through some of the deep stuff. The variation is when you get in the car , when you sit sideways and bang your feet together before you swing inside. The usual rhythm is a one, two, three and a quick glance at what’s fallen off! Everyone does it, its all the rage!!!!!!!!