This CafePress store sells t-shirts with offensive messages spelled out in "binary" (binary representations of ASCII characters, I'm guessing), including "Fuck Karl Rove," "Bomb, and "I am a Terrorist." Link
Update: Erik sez, "I'd get one with a truly random string of Characters on it. When asked what it says, I'd say "nothing, it's random ones and zeros." Which will mean, of course, I'll be thrown off the plane for having a shirt that says nothing meaningful whatsoever. What a lovely and useful precedent!"
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.