You'd have to be a silly billy to shoot yourself in the foot.
It would hurt and you would injure yourself. That's just what Gordon Brown did on a pre-election political tour. He was never the greatest at PR and this interview was perhaps the final nail in his political coffin.
Not only did he call the labour voter a bigot (which she is!) but he returned to his car and left his microphone on for the whole nation to hear. Katastrofa!
Bigot: somebody with strong nationalistic or racist opinions.
Poor Gordon, he really did shoot himself in the foot!