In a truly shocking moment, Will Smith just smacked Chris Rock in the face after the comedian made a joke about Jada Pinkett Smith at The Oscars. Chris was up on stage Sunday presenting for Best Documentary, but before he started naming the nominees ... he was firing off zingers to the crowd, and eventually landed on Will and Jada Pinkett Smith. Chris made a comment about Jada's shaved head ... saying he couldn't wait to see 'G.I. Jane 2' -- which got some groans from the crowd, to which he just sorta shrugged off. Chris didn't think he'd crossed...