Max reveals the false neck.
Protective item worn under a polo neck sweater as a precaution against strangulation.
Maxwell Smart employs the "old false neck trick" during his search for the KAOS assassin known as "The Choker".
The false neck is an ingenious device made by the Ingenious Device Department from an idea Max had when the laundry sent back his shirts with too much starch in the collar.
[Episode #36: "Casablanca".]