Or, at the very least, the origin of the name, which I hadn't known before reading this article.

http://www.post-gazette.com/magazine/19990727jock1.asp

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There is a breed of fan so avid that they'd want to more than see a pro's used supporter. Don Talbot sold a couple last year at his Sports Expo shop in Overbrook, which he says has the area's largest selection of sports memorabilia, especially "game worn equipment."

"Most people want a jersey or a helmet or something they can physically sit out in their house and not be embarrassed by," he acknowledges. But he knows all kinds. So when he got his hands on four Steelers jocks last year, he put them in the clear plastic display cases made for baseballs, and sold all four. You know, discreetly.
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