If champú is one household word that Spanish borrowed from English in the 20th century, jeans is another. Depending on which part of the Spanish-speaking world someone is in, the word has been imported as jeans, blue jeans, or bluyín. Like pants, of which [blue] jeans are a type, the word jeans often appears as a plural in English because the garment has two legs; that’s why we can speak of a pair of pants or a pair of jeans. Because cowboys wore (and still wear) jeans, the Spanish of Spain often uses the term pantalones vaqueros or just vaqueros instead of any form of jeans.
Just as shampoo wasn’t originally English, neither was jean, which Middle English adopted as jene; that was short for jene fustian, where fustian is a type of twilled fabric. The jene came from Genes, the Old French name for the Italian city of Génova/Genoa, which is where the material presumably originated.
© 2011 Steven Schwartzman