By stating—with blank as a kind of rhetorical fig leaf—that Schiff couldn’t carry Pompeo’s jockstrap, Trump was using a long-standing idiom, popular especially among athletes and sportswriters, to say that Schiff is Pompeo’s inferior. With an air of macho bluster, Trump seemed to be striving for a kind of alpha-male domination. While this may be an example of Trump’s penchant for “locker-room talk” (as he and his supporters explained away the crude, sexist language on the Access Hollywood tape in 2016), the president pulled his punches by self-censoring the jock element. But why might Trump think that jock would be deemed by his critics “so terrible to say”?

Answering that question requires taking a more intimate look at the jockstrap, both the physical and metaphorical kind. Jock has historically had several intertwining meanings. As a nickname, originally in Scottish usage, “Jock,” like “Jack,” could be used as a pet form of John. Jockey started out as a diminutive version of the name Jock, and by the 17th century, jockey came to be used for professional riders of racehorses. (Later, in the 20th century, jockey got transferred to other professions, such as radio “disc jockeys.”)

Meanwhile, jock developed on another track as coarse slang for genitalia. Jonathon Green, the author of Green’s Dictionary of Slang, derives this meaning of jock from an earlier slang term, jockum. Green takes jockum all the way back to the 1560s, in a treatise about vagabonds in England that includes the line, “He tooke his Jockam in his famble, and a wapping he went.” (Mark Morton, in The Lover’s Tongue: A Merry Romp Through the Language of Love and Sex, helpfully glosses that line as “He took his cock in his hand, and a-fucking he went.”)

The shorter form, jock, originally could refer to genitals regardless of gender. A dictionary of “cant” (the secret language of London’s criminal underworld) from 1790 defined it as the “private parts of a man or woman.” But over time it became a strictly male term, likely influenced by the man’s name Jock. Green cites various bawdy British songs of the 19th century, such as “Said a Quim to a Jock,” an imagined dialogue between male and female genitalia.

In American usage, the old coarse meaning of jock did not make many inroads—except in the case of the jockstrap, an undergarment designed to protect a man’s genitals from injury during athletic activities. According to the indispensable reference Cultural Encyclopedia of the Penis, “An early version of the jockstrap was developed in Chicago in 1874 by C. F. Bennett for the sporting goods company Sharp & Smith,” but it is unclear what it was originally called. The earliest known appearance of jock strap, as provided by dictionary editors at Merriam-Webster, is in an 1886 Peck & Snyder Sporting Goods catalog. An item in the catalog reads:

No. 900.—Jock Strap, used more by gymnasts, athletes, rowers, etc., made of fine cotton band, bag of sateen lined with fine cotton; size of band regulated with buckle, and strings, to tighten the bag, by fastening through eyelet holes. Price 50 cents.

That same year, however, a similar undergarment was being marketed as a “jockey strap.” An advertisement in The Boston Globe for a sporting-goods store offered jockey straps for athletes playing a kind of roller hockey known in New England as polo. Wright & Ditson’s Polo Guide, also from 1886, makes clear what jockey straps were used for: “Every polo player should wear Jockey straps to prevent rupture.”