"Here's an interesting fact about the popular Christmas hippopotamus song - in 1953 a ten-year-old girl from Oklahoma, Gayla Peevey sang the song as a way to raise money for the Oklahoma City Zoo's first hippopotamus. It became a nationwide hit after that."
I don't think it was written specifically for this event but it was this event that made it big!
I guess every year they put on a free performance and showing of their hippopotamuses. It will be this Saturday at 2pm, I wonder if I could talk the hum-bug into fighting the crowds and seeing the Hippos.