A slang term for, usually, a rabid fan of comic books. Stereotypically, fanboys are the guys you see who wear comic book T-shirts, spend every last dime they have on new comics, are capable of arguing the finer points of comic book continuity for hours on end, and have more important things to do than bathe. The truth, of course, is much more complex: most of us shower every day.

I've sometimes heard the term used to describe everyone from roleplaying game fans to Trekkies to Linux geeks, but the default value seems to be comic book nuts...