Real but funny

This is a real incident but it is funny. That is why I am posting it in Jokes forum. About a year back, I and my classmates went somewhere with a professor of ours. It was an outing. The professor's wife was also with us. One day we went to a fair. My friends were enjoying. But I was mostly in one place, keeping quiet.

Sir saw this and said, "Hey, why don't you also enjoy? Go and enjoy."
He showed me that large vetical wheel(charkhee), in which people sit in chairs and it rotates. He said, "Go and enjoy on that."
I was 18 then. I thought that I was too old to enjoy such things and only children should enjoy.

I said, "Sir, when I was small, then I enjoyed such things. But I do not think I should enjoy in this age."
Sir said, "No, no. You are not that old."
I said, "Sir, it is OK. I think you and madam(his wife) can go there. I will wait here. No problem."
He burst out laughing. I was wondering why he was laughing.

We came back. Next day, in college, he was telling other teachers about the incident. He said, "This guy did not want to enjoy on that wheel because he thinks he is too old. But he was suggesting me and my wife to enjoy. But we are much older than him."

Then I realized why he was laughing. 😆