You said Mister Miyagi did it. [ Sorry, Mister LaRusso, but your memory is right: Robby was paying good attention at that time, and he does remember that. So he's confident to give his sensei a friendly punch to the arm, no power to it, lips pulled in a sly way. ] C'mon. He can do it, but you can't?

[ No way, Robby won't stand for this.

Instead: ] In skateboard, if you fall off your board, you get back on again. That's how you learn.

[ It's not a Mister Miyagi saying, but it hits the right note, doesn't it? Especially when Robby says it so sincerely....or enthusiastically.

(Yes, he can be genuine and have fun at being the "sensei" of the day, why do you ask.) ]