Cop Out is Kevin Smith’s blatant homage to the John Badham buddy films Stakeout and The Hard Way, and the picture gives many chances for stars Bruce Willis and Tracy Morgan to yuk it up.  But Cop Out’s success lies in the unforced interplay between the two stars, and Willis explains why the chemistry between him and Morgan works in the movie.  (Click on the media bar to hear Bruce Willis)

Cop Out nationwide Friday.