Heiferpotamus

mystical cross between a heifer and a hippopotamus

Tom: I was over at Griffin's the other day, and there were these two babes by the pool. The first was a unicorn, and the other one was a heiferpotamus.

Greg: Oh, really? I guess the heiferpotamus was the cow's first child.

Tom: It would have to be the first to be a heiferpotamus.