To a persistent natterer in the audience:-

Me: "Excuse me sir.....yes you sir. Haven't I seen you before?"

Him: Errrr, no, I don't think so"

Me: "I'm sure I have seen you before, I never forget a face"

Him: (turning a bit pink) "NO, we've never met"

Me: "AH YES! I have it, I've seen you on television. Ladies and gentlemen, we have a celebrity with us tonight. Please give a big round of applause to (pause for effect)....INTERFERENCE".

Big laugh, and silence for the rest of the set.

Don T.