This username is close to a decade old, and, barring a possible capitalization of the first or all letters, has the same format no matter where I'm using it. Never any spaces, and always with the numbers at the end, even if they are unnecessary.
It all started back in the Runescape days. My name is Chad A., and I had no ideas for a username. I figured, hey, why not just use "Chada"? But that was too short or already taken. So then I decided to just double it, "Chadachada." That worked for Runescape and a couple of other sites. When making my Xbox gamertag, however, some asshole had already taken Chadachada, leaving me with a conundrum. So I stuck "123" to the end, and have been using that username ever since.
It's really easy to remember, and is constant throughout pretty much every site I use. I've had only two people ***** about the numbers at the end during the past seven years, and they were your standard elitist PC gamer assholes. The numbers do not bother me in the slightest, nor do I see a reason for it to.