The hippo's real name is, "One Hung low", some zoo keepers called him by his nickname "One".

Other zoo keepers called him "Neo" or "The One", from the matrix, "You are Neo. You are the One" quote. Neo is after all an abbreviation of One.

A few weeks after the castration, The zoo keeper caught "The One" firing blanks over the fence at the female hippo's.

At the same time "The One" was heard shouting over the fence "Dodge this" (Another Matrix quote) to the female hippo's.

Poor old "One" was put down a few weeks later.