A variant on he word noob or nub.

It implies that the person being called it is American and therefore stereotypically fat and aggressive. Which are traits hat hippos also have as well as Americans.

It originated in 2007 Sep 18th when I was bored in school and made up a random word.
American (Out of breath from talking): WTF I just got pwned again.
Non american: Thats because your a noobapotamus.
by Ryan Riggs September 19, 2007
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