Ever tried registering on eBay with a username that contains the word "eBay"? If you haven't then well you gotta try to it experience this chicken and egg kind of problem (well, not really.. :)).

Anyways my point is, eBay returns an error indicating that you cannot use an ID that has the word eBay but again returns few username suggestions that again have the word "ebay" in them. Isn't that funny ;-)
See the image above. Click on it to view the original size.