if you want to sent him a message then the URL looks like this:
https://www.buzzerbeater.com/community/bbmail.aspx?showType=Create&user=%E2%80%8B
The part
%E2%80%8B
is URL-encoded. When you decode it, it becomes the Unicode character U+200B, which is a zero-width space (an invisible space character).
-> https://en.wikipedia.org/wiki/Zero-width_space
BB should ban this Unicode character as club name and managername