In game name is TheRealAlGore
I changed my name to match my outfit I just made and I didn't know that I couldn't change it back for 30 days. Apparently the name isn't allowed due to Al Gore being a political figure (although I made it look like a character from South Park).
I'm guessing that is why the name was banned or maybe it belonged to someone else who had banned in the past?
...I was just not able to log in within a few minutes of changing the name. Also Mojang has not responded about getting my old username back (ImAWalkinHere) so I'm not sure what else to do besides appeal.
Edit: This is the first public server I have played on and I wasn't even aware there was a list of rules somewhere.