Facebook is notorious for constantly making changes.  Supposedly it keeps the users interested.

There’s a new beta language setting that might be of interest to users.  You can now change your preference to English (Pirate).

Sean Malarkey demonstrates in this video:

˙sıɥʇ ǝʞıl ʞool ƃuıɥʇʎɹǝʌǝ sǝʞɐɯ ɥɔıɥʍ ‘ƃuıʇʇǝs (uʍop ǝpısdn) ɥsılƃuǝ uɐ uǝʌǝ s,ǝɹǝɥʇ

Both of which would make for a great prank if you get access to a friend’s profile.