Autoreference

A man stands in front of a building with a megaphone, some other men surround him. The sirens wail in the background, serious people who look a bit nervous and use codewords a lot are bustling about, trying to look nonchalant.
A man with a megaphone raises it and looks towards a window, where a man is standing. He's seen to have a pipe in his mouth and is holding a pencil.
-So, what are your demands? - the megaphone man hollers.
-I want everyone to think that I'm not a terrorist, - the balaclava man replies promtly, and then his voice takes on overtones of gleeful menace, - or I'm gonna change one lexem in the definition of "terrorism" every hour!
The megaphone man steps back and consults another man, who is standing nearby:
-Well, then, what do you make of it?
-Oh, I don't know, - the other man replies. - This self-reference is some tricky stuff. But we already have our best men on our way here.
-You do? - the megaphone man looks genuinely surprised.
-Indeed. I'm just off the phone with Douglas Hofstadter, he said he can be here in 40 minutes.
-Oh, hell. Mr. Terrorist, you're officially doomed.

PS
It didn't work so well: when Mr. Hofstadter finally came, he could only come arbitrarily close to finding a solution.
PPS
Then it got from bad to worse, since he discovered that the guy really wasn't a terrorist, but then proved that it can't be proved.