Japanese author/translator Hiroko Yoda was having trouble signing up for a Facebook account. Every time she tried registering with her real full name, she got an error message. She suspected that it might be because of her last name was Yoda, so she tried spelling it slightly differently—Youda, Yohda, Yooda. No problem at all. When she e-mailed FB explaining her situation, she got this reply:

Facebook blocks the registration of a number of names that are frequently abused on the site. The name "Yoda," also being the name of a popular Star Wars character, is on this list of blocked names. I apologize again for the inconvenience. Please let me know if I can be of any further assistance.

http://www.boingboing.net/2008/08/26/japanese-with-last-n.html