HippoPOTamus? HippopoTAYmus?

[Green Bean]

My coworker says that he pronounces the word "hippopotamus" as "hippopoTAYmus." He claims that this is a British pronounciation. He's from Ghana, so he does pronounce some things Britishish, and some other things just sound odd to us because of his accent. Like the time he told us he just bought a new shit. (it was a new shirt.) It's okay that he talks a little funny. We can't all be lucky enough to be native New Yorkers.

But this hippopoTAYmus thing? I find it hard to believe. Is this a legitimate alternate pronounciation, or is he full of...hippopoTAYmus shirt?