Im not sure how to go about this. C is 15 months old and thinks its HILARIOUS to whack people in the face and head. We've been grabbing her hands and firmly saying "No, we do not hit" and she will crack up laughing at us like it's the funniest thing in the world. She thinks its a game.

Its gotten to the point where she hits really hard and she has even scratched my eye doing it.

How do I stop this behavior? Im lost.