Etymology First attested around 1950. Unknown origin, likely imitative, of echoic origin.
1
Slang An unfavorable card or token, or undesirable or worthless item used as a prize in a contest or game show (such as Let's Make a Deal).
There will always be two doors that hold zonks, so regardless of whether you initially chose the grand prize or a zonk, Monty will always be able to show you a zonk not chosen.2003-10-1, Gregory Arthur Baer Life: The Odds (And How to Improve Them), Penguin, page 237
A live, mane-embellished, SAG-card-carrying lion, I should point out, who was likely being staged for a few minutes off to the side before he would be used as a freaking “Zonk!” on a freaking game show, for crying out loud.2003-12-30, Jerrilyn Farmer, Mumbo Gumbo: A Madeline Bean Novel, HarperCollins, page 204
4 more examples
A zonk was way overdue, yet the boys knew that the Seniors knew they would think this was a zonk and would trick the boys by making this another real prize.2004, Jay Mechling, On My Honor: Boy Scouts and the Making of American Youth, University of Chicago Press, page 124
I have three empty coffee cans, two with prizes and one with a slip of paper that says "Zonk."2004, Timothy V. Rasinski, Nancy Padak, Effective reading strategies: teaching children who find reading difficult, Pearson/Prentice Hall, page 150
Avoid the Zonk / On the TV show Let's Make a Deal, contestants often had to choose between three curtains.2006-05-09, Bruce Frey, Statistics hacks, O'Reilly Media, page 208
Once a contestant picked a door, Monty would often open one of the other two doors to reveal a zonk, […]2008, Max H. Bazerman, Don A. Moore, Judgment in Managerial Decision Making, John Wiley & Sons, page 53