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1.
a lifelong enemy, where your "enemyship" is so strong that over the years the two of you have become close friends in an awkward sort of way. The two of you of course would die rather than be seen smiling together in a photo on Facebook.
Chrissy is my mortal enemy...we hate each other's guts but we also know that it's not a great outcome if we fail that upcoming exam, so we'll just pretend to be nice for a little bit and then go back to our standard relationship when it's all done and dusted"
by jennyberry June 06, 2014