During the 1600s and 1700s, 'calzoons' became an accepted way to refer to foreigners' underpants. The word is a corruption of the many different words for underpants descending from the Latin calciones, meaning stockings or hose; French uses calçons, Spanish calzones, Italian calzoni, etc.
When English-speaking travelers needed a word to describe the unfamiliar undergarments of Turkish, Asian, and other odd peoples, they tended to go for the average foreign-sounding word, something like calsouns (1615), calsounds (1656), calsunes (1656), and calzoons (1677); over time, calzoons became the preferred form, and then the official form. The Oxford English Dictionary includs the definition "drawers, hose, trousers: used of those of oriental nations." It is currently thoroughly obsolete.