You're Will Smith, and you want to discipline / punish Chris Rock for making an off-colored (or hurtful) joke? A joke with the official sanction of the Academy Awards show?
You take your wife and family and immediately and quietly leave the venue.
Chris Rock would have profusely apologized, but would still never have heard the end of it.
Even better that Will Smith would then not have been present to pick up his award!
Regards,
From what I read today, Rock didn’t use that joke in the rehearsal.