Overview
xkcd is a webcomic created by Randall Munroe. In comic #426, published on 21 May 2008, it presented an early version of the algorithm for Geohashing. Such spontaneous GPS-based adventuring was also hinted at in comic #201, published on 25 December 2006.
The latest installments of the comic, which are published on Mondays, Wednesdays, and Fridays at 00:00 ET, can be read at xkcd.com.
See also
Remember, to crash 'slackware', the easiest way is to say melon-the wood elves' (wood elves are a Sindar tribe) word for friend. (Used by Gandalf to open a dwarf gate to Moria.) Also, laugh at the comic, not how it can be applied. Especially the one about the settlers that cannibalized.