Think of your favorite character from a movie or a book you've read or just make something up out of your head. Lot's of things to snag a username from. You have a good head on your shoulders, you'll think of a good one. Maybe something from one of your blogs even.
If you have any nicknames, you could use one of those. Mine always has 'Toad' in it, well, except for here. You could pick something you love, like a sport, a band, a tv show character, a song, etc. Don't worry, you'll think of the perfect username. It just might take some thinking and time:)
make it out of 2 parts: 1. Something people are really into 2. Something funny.