"Hoi polloi is Greek for "the common people," but it is often misused to mean "the upper class" (does "hoi" make speakers think of "high" or "hoity-toity"?). Some urge that since "hoi" is the article "the hoi polloi" is redundant; but the general rule is that articles such as "the" and "a" in foreign language phrases cease to function as such in place names, brands, and catch phrases except for some of the most familiar ones in French and Spanish, where everyone recognizes "la"—for instance—as meaning "the." "The El Nino" is redundant, but "the hoi polloi" is standard English."

From a dictionary on the net.