I was messing around on the Nike store trying out the "made to order" Nike+ shoe section. There is an option to label your shoe with your "iD". When I tried "Joi" it said iD declined. It accepted "Jo", "Joichi", "JoiIto" but not "Joi".
According to their policy:
A Personal iD may be declined for any one of the following reasonsSo what does "Joi" mean that I don't know about? :-\
* It might violate another party's trademark or other intellectual property rights. These may include words, phrases, celebrity's names, and even certain color combinations when used in connection with particular words or geographic designations.
* It contains profanity, inappropriate slang, might be considered insulting or discriminatory, might be construed to incite violence, or may simply contain material that we do not wish to place on our products.