This song goes back a long ways -- try 1953! But it remains one of the most memorable and delightful of that long list of Christmas novelty songs that have been recorded over the years.
The song was written by John Rox (1902–1957) and was wonderfully performed by 10-year old Gayla Peevey.
A local promoter in Gayla's hometown (Oklahoma City) followed up the national popularity of the song (it hit the top of the charts that December) with a campaign to present Gayla with an actual hippopotamus on Christmas.
And the campaign was a success! (Imagine Mom and Dad's first reaction to that news.) But Gayla wisely donated the baby hippo to the Oklahoma City zoo.
The hippo, by the way, was a featured attraction there for nearly 50 years.
But enough trivia. Here's the original song as I first heard it in my pajamas as a two-year old kid.