To further demonstrate their boundless awesomeness, once the sun goes down bonfires are lit and the cows are forced to jump over them. This may seem strange, but you have to remember that cows are sacred, and not to be eaten. If we couldn't eat cows, we'd probably make them do some pretty weird s**t too.
Gotta do something with all these cows.
Like any good festival to celebrate the harvesting of the summer crop, Holi traces its roots back to a demon king. This particular demon, angry at his son for worshipping Vishnu, tried to set him on fire and instead burned his sister. Presumably, everyone in attendance stared at the floor in an awkward silence until some enterprising young soul said "Welp, might as well party." Thus, Holi was born.
Nowadays, various peoples in India, Nepal and elsewhere celebrate Holi, the Festival of Colors, by hanging pots of buttermilk above the street so that children can form human pyramids to try to break them. Lest you think it's as simple as that, it should be noted that girls will also be throwing colored water at them at the same time. It's sort of like a wet t-shirt contest, but with children, and the water is full of dangerous chemicals, and everybody loses.
In retrospect, this is nothing like a wet t-shirt contest.
That's part of what makes Holi the Festival of Colors, the prevalence of colored waters, pastes and powders which regular folks just seem to toss at each other all willy nilly. And while it only seems like a minor annoyance to have someone throw a pot of red or blue water on you, when you factor in that some of the ingredients used in the modern colors (like asbestos) can cause renal failure, blindness and various cancers, it hardly seems worth it to bust open a pot of buttermilk and be named the King of Holi.