A Klunk! is an unwanted booby prize on The New Treasure Hunt and Treasure Hunt (1981-82 version). Similar to the Zonk on Let's Make a Deal, and the Chasco on Trato Hecho, these were worthless and ridiculous joke prizes that were often used for comedic value.
Background[]
Treasure Hunt originally aired from 1956-1959 on ABC, with Jan Murray as host, where contestants selected a box and won their contents. Much like the Chuck Barris-produced version, some of the boxes also contained gag prizes or prizes of a very small value, although these were not referred to as Klunks!
In the Barris-produced shows, an undetermined number of boxes among the 30 (1970s version) or 66 (1981 version) boxes hid klunks. However, each box was tied to a skit, which eventually would determine what the contestant won. Invariably, these skits were written in a way such as to lead the contestant to believe she had had won a Klunk, although that was a cover for what was eventually revealed as either a legitimate prize or another Klunk. (Host Geoff Edwards would signal the end of the skit by placing the box on its side, with the lid removed.)
Much like the Zonks seen on Let's Make a Deal, the Klunks varied widely, and were presented with a Moog-synthesized musical cue as announcer Johnny Jacobs described the prize (often having a low dollar value, well below $50). When a contestant chose to keep the cash amount and a Klunk was revealed as the box's contents, Edwards would -- as he was congratulating the contestant -- often say, "You beat us out of a Klunk."