In West Philadelphia there was a group of Irish red-headed boys hiding in the bushes at the top of the hill, by a stop sign.  They took their hiding places as soon as there was a half inch of snow on the ground.  Once the cars were stopped, the boys came running out in groups of two or three and "hopped the car."

I was one of those boys.  We would hang off the back of stranger's cars as they pulled us along in the snow.  There were a few outcomes: (1) we scared the drivers and the passengers and they started yelling at us to get off the car, (2) they saw us and sped up, or (3) they just pulled us along.  

The problem with being pulled along was that sooner or later we'd hit a clear patch of pavement, lose our footing, and go down.  This was hard on our jackets and required a lot of explanations when we got home minus our buttons!