Punk, noticing my choice of words: "My friend? Are you my friend?"
Me, after pausing to think that I am not supposed to be my child's friend; I'm supposed to be his parent. But this probably won't be a factor until his teenage years and then it'll be too late anyway. So to simplify things, I answered: "Yes, I am your friend! Are you my friend?"
Punk: "No. I'm not your friend. I'm your Calvin Boy."
So he gets it.
And now, here are today's swimming lesson videos for your viewing pleasure.