Washboarding is well documented and continues to fire beekeeper’s imaginations.
Here’s one specific take on this intriguing behavior: “Worker honey bees exhibit a ‘group’ activity known as rocking or washboarding on the internal and external surfaces of the hive. This behavior is believed to be associated with general cleaning activities but virtually nothing is known as to the age of worker engaged in the behavior, under what circumstances workers washboard and the function of the behavior. We investigated the frequency of washboarding behavior in relation to worker age, time of day and surface texture.”
Nothing communicates this behavior as perfectly perhaps as this video from Jim Tew, retired Ohio State University Apiculturist, now representing Auburn University.