My username used to be This User Has Been Banned, but I changed it in order to not actually get banned (well, blocked).
Most of the work I do on Wikipedia involves reverting disruptive edits/vandalism (I patrol Recent Changes) and warning users if they make edits that don't look constructive. I also like to do some copy editing, and occasionally try to add sources for articles.

Userboxes

This user is a female contributor. This user is a member of the Guild of Copy Editors. This user qualifies as a nerd extraordinaire. This editor is a Grognard Extraordinaire and is entitled to display this Wikipedia Vest Pocket Edition. This user is mortal. This user is a history buff. This user is a participant in WikiProject Articles for improvement. This user fell down a rabbit hole known as Wikipedia and can't get out. This user has participated in 2 Backlog Elimination Drives with the Guild of Copy Editors. This user is an agent of the Counter Vandalism Unit. This user is a recent changes patroller. This user is a member of the WikiProject Unreferenced articles. This user believes that one should never stop feeding one's brain. This user may suffer from Compulsive Wikipedia Editing Syndrome. WikiProject Editor Retention can help This user has both RedWarn and Twinkle, and may use them together! RW This user is crazy. Feel free to whack them with a wet trout. sar This user is obviously not sarcastic. This user currently resides on Planet Earth. This user thinks, therefore she exists. This user believes in logic. This user likes spiders. This user is nosy. In fact, they're looking at your contribs right now. This user would like to know what a black hole looks like from inside, but doesn't want to investigate it personally. This user knows global warming is a reality we are facing. This user is completely addicted to chocolate This user is an idiot, and they are proud of that. ... This user may get around to being a professional procrastinator. Someday. Maybe. This user spends most of her free time thinking about random things... OH SHI– Prime number are numbers with only 2 factors, 1 and [citation needed]. This user knows the dire side effects of dihydrogen monoxide. Do you? Sellout This user watches the Super Bowl for the ads. Oh no: this user has way too many userboxes. This user believes sleep is for weaklings! Do not come to this user while wearing a tinfoil hat. This user will never give you up, let you down, run around or desert you.