The closest thing I have to a signed hat is a something written on the box that the hat came in. No other box from them has had that, so far.
NSA's cheeky.
Way easier.
Battlestar Galactica's ultimate ending (2000's reboot) shows that the whole thing has been:
The Answer to Isaac Asimov's "The Last Question".
Flips the ending from "cop out" to "fuckin' genius".