Once modified to suit a space theme -- it was a tour around the galaxy to different planets, people traveled in a spaceship to get from planet to planet (a drawing of the USS Enterprise, no less,) and they went back to the starbase. But essential details of the dialogue and, of course, the joke itself, were exactly the same.
Cast: Guide, Tourists, Echo hidden in the bushes
Setting: A Tour of the Countryside
You might want to lengthen it a bit at first, to tell a more complete story, but for the sake of brevity, you might not.
Guide: (To tourist group) And this over here is the famous site where John Smith first discovered gold. Now if you'll follow me, we'll be going to Echo Point next. (Walks around a bit with the group.) Here it is. What makes Echo Point so special is that whenever you call out the name of a food, it will echo three times. Listen. Yogurt! (Echo: "Yogurt! Yogurt! Yogurt!") See? Now, would anybody else like to try?
Tourist #1: I would. Banana! (Echo: "Banana! Banana! Banana!")
Tourist #2: Salad! (Echo: "Salad! Salad! Salad!") Hey! Neato!
Tourist #3: I want to try. Baloney! (Echo: "Baloney! Baloney!" -- ONLY TWICE!)
Guide: (After a pause,) That's strange -- it's never repeated a food only twice. Maybe we should wait a moment more. (Pause -- nothing happens.) I'm so embarrassed. Well, I guess we should go back to the base, where the food is so good!