Cracked magazine that sailors visiting Asia probably came up with it, since they already believed manatees were really hot mermaids.
I mean who hasn't heard about , but -- sideways vaginas? But underneath their scales, they're just like you and me.
Thus, by want of opportunity to put it to the test, the legend of the sideways' vagina is maintained.
Ah, the power of the Internets! Filter posts by subject: Please use spoiler tags to hide spoilers.
It may have arisen from the interface of the Chinese with the English, who took over Hong Kong in the 1840s.
Probably just extremely horny, actually.