<human>:  When did the one-piece bathing suit come into fashion?
<bot>: The one-piece bathing suit was invented in the 1920s. The one-piece bathing suit was designed to be more comfortable than the two-piece bathing suit, which was popular at the time. The one-piece bathing suit was popularized by the movie “Gentlemen Prefer Blondes” in the 1950s.