The DWTFYWWI license is a parody of the GPL I wrote in 2006. It's used by a few small software packages (mainly in MediaWiki).
I don't use the DWTFYWWI license myself, mostly because I'm usually working on projects that are already under a different license. Or projects that need to use libraries that prohibit these sort of terms.
If you want a less humorous (and less vulgar) but permissive license you might want to check out the MIT License, or the public domain terms SQLite is distributed under.
Ævar Arnfjörð Bjarmason avarab@gmail.com