Big Brother’s Julie Chen Moonves Reveals Origin of Famous Catchphrases (Exclusive)

Julie Chen Moonves tells ET the origin of her famous catchphrases, including 'expect the unexpected' and 'but first.' 'Big Brother' season 25 premieres Aug. 2 on CBS. ET's special, 'Big Brother: 25th Anniversary Celebration,' airs July 26 on CBS.

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