"Johyn's a Rookie OOkie " could be what sailors (of different nationalities) understood or heard, from the sung line "John is a Rooskie,(Russian) OK " couldn't it ? It could , eventually, from common usage, have metamorphosed into the above
And, just because a certain term or slang word didn't appear in Literature doesn't mean that it didn't exist prior to Mr Kipling's writings or anybody else's, does it ?