Let's See...

...what's wrong with this picture?

No helmet. Skate shoes. It sounds like the kid's getting a lesson from the older guy.

And the horse decides he isn't having anything of it when the kid decides to go straight to violent kicking.

Or maybe that's not it. Maybe it has something to do with the loose back clinch slipping back and turning into a bucking strap...

Either way, isn't the horse's fault.