Ever since the Paleolithic period, squirrels have lived among the horse. Horses and squirrels have always been close friends and have shared everything among themselves. Squirrels gave their acorn findings to horses for food and horses gave the squirrels fertilizer to help the trees grow bigger acorns. It was symbiosis at it's finest hour.
One day, Horses developed wings and because known as the horsefly. As the squirrels became jealous of their friend's new found talent, they were sorely afraid that the horses would fly away and never return, thus losing the big cash cow of oversized acorns!
(This seemingly playful term, "Cash Cow", was really never meant to be a compliment. It was meant, instead, to vehementaly let the cows know (The horse's arch enemy) how much they were hated and not welcome around the acorn farm. Besides, the squirrels were lactose intolerant... very intolerant!)
The horse, sensing this fear, assured the squirrels that they were close friends, and true friends would not hang each other out to dry. They told the squirrels that they would only be gone during the winter to get out of the cold, but would promise to always return for the summer.
The squirrels were still afraid and crying becuase they couldn't fly either. The horses, had pity and decided to impart their special unicorn power to give the squirrles wings. This way, in the winter, they could fly down to Miami and enjoy the winter together.
This lead up to squirrels eventually losing their wings and moving under water in a space suit, as is documented, by the squirrel living on Sponge Bob's Squarepants, but that's another story for another time.
The End