Actually I think she says "I had no clue" before the slap.
You're right, that does look fake, especially the way he is hiding his face and hanging his head afterwards.
The other one though, the one on the basketball court....ow, that was for real.
I think it's the very rare person who wants an entire auditorium of people to be in on their proposal.
If the couple is under a certain age, like under 25 or maybe 27, I think it's a huge gesture of respect to asks the girls parents for their daughters hand in marriage first.
It's not like it's meant like generations ago, when the daughter was chattle. It is an opportunity to express to her parents how you want to spend the rest of your life with her, and that they will never have to worry that she won't be treated well.
Some things just never go out of style.
A co-worker has 3 grown children, all married now.
The one daughter, R. has been married twice. Tragically, her first husband died in a car crash when they were only married a little over a year. I know that both times the husband to be asked for her hand.
I think the 2nd time was even more emotional for everyone, because it was saying that he knew the daughter was capable of making her own decisions, but he wanted the parents to know how much he thought of them.
I think it's amusing that someone would think it was all right to ask someone they love to marry them via a billboard or over the PA system at a football game, but would worry about feeling foolish in asking the people who raised his beloved for their blessing.
Anyway, my opinion is that this is a very private moment, for just the 2 people involved.