This happy occasion commemorates the day on which the word cocktail first appeared in print. That was May 13, 1806. Harry Croswell (1778-1858) was the man who first put pen to parchment, or something to that effect, and spelled out the word cocktail.
Yes, that day in May is rapidly approaching. Celebrate it as you will of course, but my recommendation is to put down those pedestrian screwdrivers and go for something original.
One place to find the out-of-the-ordinary is the Qantas Business Class Lounge in Hong Kong, where the bar features special cocktails. The offerings are changed periodically, and as you can see from the picture below, they are original and meticulously prepared.
Drinking Japan 