"I went into this pub, and I ate a ploughman's lunch. He was livid."

That's how they've got it in that first link I gave, and I think that "livid" somehow adds the signature.   Especially if you have Tommy Cooper's voice running in your head. (What a disconcerting thing to have...But when I looked and listen to those video clips, I found he tended to stay around when I read the jokes.