I did a similar thing at a place I worked at. In order to go over the heads of insane management and actually get work done, rather than just have sugar cubes counted at me all day, I created an administrator account with the username of  .

Not blank. The character " ".

What, you can't see it? It's a non-breaking space. You can type one (on a Windows machine) by holding Alt and pressing 0160 on your number pad.

A shocking amount of "enterprise" software is not equipped to handle a non-breaking space, and will not detect it as a naughty character nor treat it as whitespace -- which is probably what should happen. So what you get is an invisible user, which is also helpfully sorted to the bottom of lists where no one will notice it, because its numerical index in character space is well below all the typical letters and numbers that'll be used for user account names. Does your software require a user name of greater-than-one character length? No problem, just type in a whole bunch of them.

Non breaking spaces can also mess with the formatting of systems with user-facing text input that'll regurgitate it later. Like, oh, forums. Or comment threads. Like this one. Even those that are "smart" and attempt to collapse repeated whitespaces into a single line break.

For instance.

Yeah, that sort of thing.