The act of running between friend's umbrellas on a rainy day quickly to avoid getting wet. Often used to get across school commons/courtyards, parking lots, or even quick walks across the street.
I was Umbrella Hopping the whole way across the parking lot!
Moving from under random people's umbrellas to other random peoples umbrellas in public because you haven't brought your own
Ugh I forgot my umbrella today and had to umbrella hop from class to class
Yesterday it rained so hard that Precious had to go umbrella hopping