While shooting Kill Bill, Volume 2, director Quentin Tarantino noticed that certain Chinese crew members were curiously keen on the phrase "niao-pei, niao-pei." Told that it meant "supercool," Tarantino decided to use it in the film.
Some time later, Tarantino learned that, in Mandarin, "niao-pei" is in fact more commonly understood to mean "cow's vagina." He promptly asked a crew member what was so "supercool" about a cow's vagina. The man's reply? "It's so... big!"