I wouldn't know. But I did see the strangest thing not too long ago when it started to rain after a long dry spell.
Our crazy horses, in a somewhat organized fashion, left the back pasture, wandered (en masse) down to the arena, and proceeded to let loose. Mind you, this is no straight forward effort. The entrance to the arena, though it adjoins the back pasture, does not benefit from a direct connection. The horses had to stop what they were doing (eating), group up, and rapidly wander down to the arena in order to cut loose as the pictures here show. Mind you, it had just began to rain when they all magically arrived within the arena. They showed up in the arena very rapidly.
We were so surprised by the size and location of this carefree exhibition that we pulled the camera out to capture it.
It is not uncommon for cooler temperatures and a little rain to spin the horses up. But they chose the arena for this playfulness. Why? Sure, the footing is softer. But it really seems they had to be premeditated and organized to do it the way they did.
They had to first "think" that they wanted to run about as the rain begun to fall. Then, it seems, one of the horses had to say to the others, "hey fellers, if we're going to jump and kick about, it would make a lot more sense to do in the arena. The ground is much softer there. And Wally, you can use the mud there to make a filthy spectacle of your yourself. What do you think? Last one there is a rotten egg!"