Submitted by Jeffery Bridgman, who says:

A bath towel with the different services (different types of local/express trains) that run on the Keio lines in Tokyo. Hilarious!

http://railf.jp/news/2013/02/22/100000.html

Transit Maps says:

Oh, those crazy Japanese! Still, one can’t help but think that Douglas Adams – whose 61st birthday would have been two days ago – would have approved. Because, after all, a towel is about the most massively useful thing an interstellar hitch hiker can have. Especially one with a railway map on it.