One day, when the three billy goats Gruff felt very hungry, they spotted the greenest grass they'd ever seen on the other side of the river. Unfortunately, an ugly old troll lived under the only bridge and, if anyone tried to cross it, would cry who's trip-trapping over my bridge? before gobbling them up. The troll was very big and very ugly, but he was still no match for the three billy goats Gruff...