Anyone generally interested in oddness and the unexplained, or who has at least read the occasional issue of Fortean Times will probably have heard of the Voynich Manuscript, a bizarre manuscript full of text that has defied the efforts of cryptographers and strange diagrams. If you’ve never seen it, it’s worth a quick click of that link to Wikipedia as a starting point.
There have been a number of possible explanations offered (again, details in the Wikiwotsit page, and elsewhere), but I think we now have the definitive answer, from none other than xkcd:
Click to see the whole story. I’m sure you’ll agree that this is the best explanation ever offered for this previously mysterious item. Mystery solved by the power of geekiness!