What's great about the Cone of Silence is that a completely corny shtick has over the years become a standard phrase in the business world for confidentiality. People use the term "this is under the cone of silence" all the time know with absolutely no intention f it being a humorous reference.

The Cone of Silence was an item used in the series "Get Smart". It was meant for top secret meetings. In practice, however, The Cone rarely worked as intended. When it appeared, slapstick was likely to follow.