If you don't vote then you automatically forfeit all rights in future Idle Banter MassDebates betwixt the "Ebil Liberal Lefty Weeners" and the "Ebil Right Wing Nut Jobs". You also forfeit the right to complain. About anything really.
Apart from anything else, someone needs to go and counter my "Ebil Liberal Lefty Weener" vote in Cheltenham
EDIT:
http://www.youtube.com/watch?v=MnWveedO42Q - Vote or Die