This was my creation back in 2010 except that it was a whole egg and the rum was Old Monk (it was created for Mixoloseum's Thursday Drink Night with a theme of "dark rum"). My inspiration was the Diablo as well as an egg drink that I had earlier in the week.; to this day, I'm still not sure if citrus invalidates a drink from being a Flip (it certainly isn't a classical ingredient).
Curated this to correct ingredients and add attribution, per @yarm's comment above. (For posterity the previous posting had Smith & Cross as the rum and an egg white without yolk.) Thanks!
