I think my username is cool! I have had many times in which I had to use a parking lot, w car wash bay, or w parking garage as a toilet. Here are a few usernames I thought were funny, but not as good as the one I have
Diarrhea of a Madman
Dropping Dueces are Wild
Big Shit
Shit of Fools
hey man Nice shit
Bohemian crapsofy
Free turd
I shit the sheriff
Shit at the devil
Shit on you crazy diamond
Shartbreaker
Hit me with your best shit
Wipe out
Shit to thrill
Shit in the dark