* July 3, 1957: Philo T. Farnsworth, the father of electronic television, makes his only appearance on the media he helped create as a contestant on this show. No points for guessing what his secret was. [[note]]At least, it was his only surviving appearance on television; Roy Southwick claims he interviewed the man back in 1953 on KID-TV's (today KIDK-TV) opening day.[[/note]]
* January 14, 1959: Jack Moseley, from Long Beach, CA, has a secret: "[[https://www.youtube.com/watch?v=mep3HTOh2Sg I'm going to inflate an automobile inner tube until it explodes... with my mouth.]]" [[spoiler:It takes much longer than expected, preempting Andy Griffith's guest segment that was supposed to follow, but he refused to give up and eventually managed to blow up the tube. Griffith went onstage regardless, since he wanted to "see 'er bust!" -- he, like everyone else, was determined to see Moseley succeed.]]
* November 27, 1961: Bernard George, chief engineer of Minitone Electronics, [[https://www.youtube.com/watch?v=xKbiXRAc47U comes in and demonstrates a miniature radio]]. After the panel fails to guess the secret, it is revealed that Betsy Palmer's watch had been fitted with an even smaller radio, which is also demonstrated. Only then does Bill Cullen figure out the secret: "[[spoiler:He is a sneaky ventriloquist!]]"