Author Jeremy Donovan's in depth study of World Champion speakers suggests if you get a laugh, you riff on the laugh. That is, you tell a similar joke, building on the successful joke. For example, World Champion Ed Tate had three jokes in his award-winning speech, each one building on the one before: "[miming a policeman handing someone a ticket]Here you go, Mr. Tate. Next time, drive a little slower. Speaking of slow, have you ever wondered why it takes so long for a policeman to write you a ticket? Completely eliminating all that time that you have made up."
Riffed,
Tim Wilson
Professional Speech Coach
Free speaking tips at: http://speakingquicktips.blogspot.com