I've been reading a book called Surely You're Joking, Mr. Feynman! for my physics class, and I thought I would share a funny story from it that I enjoyed! One day, when I had my earphones on, I connected them to the loudspeaker, and I discovered something: I put my finger in the speaker and I could hear it in the earphones...like a microphone, and you didn't even need any batteries....So I now had a microphone, and I could broadcast from upstairs to downstairs...At that time, my sister Joan, who was nine years younger than I was, must have been about two or three, and there was a guy on the radio called Uncle Don that she liked to listen to....One day my cousin Frances and I sat Joan down and said that there was a special program she should listen to. Then we went upstairs and started to broadcast: "This is Uncle Don. We know a very nice little girl named Joan who lives on New Broadway; she's got a birthday coming..." We sang a little song, and then we made music: "Deedle leet deet, doodle doodle loot doot, deedle deedle leet, doodle loot doot doo..." We went through the whole deal, and then we came downstairs: "How was it? Did you like the program?" "It was good," she said, "but why did you make the music with your mouth?" -Surely You're Joking Mr. Feynman, page 25.