One such license is the WTFPL—better known as the Do What the F*ck You Want to Public License.
Written and released in March 2000 by Banlu Kemiyatorn, this copyright license is for all intents and purposes identical to Public Domain, but takes a slightly more profane approach to its wording.
As stated in its Wikipedia entry, the WTFPL license ‘allows for redistribution and modification […] under any terms – licensees are encouraged to “do what the fuck [they] want to”’.
Considering the license is essentially Public Domain and its name isn’t exactly family friendly, it’s not much of a surprise that the Open Source Initiative decided to exclude it from their license list.
Still, it’s undergone one major revision, with version 2.0 and a French translation being released by French programmer Sam Hocevar in 2008 and 2009, respectively.
I’m not sure how many people would use it, but I would very much consider licensing my photos under WTFPL on Flickr if possible. Would you?
P.S. if you are wondering if you can actually use an image which is not WTFPLed, this would be a good place to start.