To be hit in face with a water polo ball so hard, the ball starts to curve the other way so it's touches (and crushes) ones face.
When the ball covers as much surface area of ones face as physically possible.
(girl watching her friends water polo game. Her friend's a goalie and blocked some pretty tough shots)
friend: Oh my gosh are you ok? That chick looked like she had a really strong arm!
Goalie: She did! She gave me a Water Polo Facial! but at least i stopped the ball. And its not my first tie getting a water polo facial.