There's a joke I don't understand. Can someone explain it?

There was an old man who had entered the city for the first time. He wanted to go to the toilet but couldn't find it, so he asked a passerby. Unexpectedly, the passerby pointed to a cinema. The old man walked to the entrance of the cinema and was about to enter when he was stopped by the ticket inspector." Your ticket?"
"Do I need a ticket to enter this place?"
"Of course, please go there to buy a ticket."
The old man thought that this city was indeed different. They had to buy tickets to go to the toilet. Hence, he bought a ticket and went in. However, he had never seen such a toilet before. He looked around and the waiter found his seat according to his ticket. The old man thought that the city was a city after all. They had to sit according to the number when they went to the toilet. However, he found that there were many people in the cinema. There were men and women, and there were lights. He was very puzzled. He asked the people around him," Are men and women together here?"
That person looked at him and said,"Yes."
He didn't dare to ask further, thinking that since this was the rule, he shouldn't break it." But why is the light still on?"
"Turn off the lights when it starts."
"When do we start?"
"We'll start after the bell rings."
The old man finally understood. This time, it was an eye-opener. In this city, people had to go to the toilet together and have their own seats. However, he still could not understand why both men and women had to turn off the lights before they started. But the delay in ringing the bell made him very anxious.
Finally, the bell rang and the lights went dark. The thing that the old man had been holding back for a long time finally happened…
I know that the old man's long-held-in-wait finally happened. It's either pooping or peeing, but it's not funny at all. I think there should be a more subtle joke, but we haven't found it.

Answer 1

Of course, this is an example of humor and jokes:

One day, a mathematician and a philosopher walked into a bar. The mathematician picked up a glass of wine and took a sip. Then he asked,"How many calories is there in this glass of wine?"

The philosopher smiled and replied,"I didn't know it was a mathematical problem that required precise calculations."

The mathematician shook his head and continued to drink." Then can this question be answered easily?"

The Philosopher nodded and said," Of course, this question can be easily answered. The answer is: it has no calories."

The mathematician was a little confused, but he still tried to understand the philosopher's answer. So he asked,"So if this drink has calories, then this answer is wrong?"

The philosopher smiled and said,"No, it has no calories." This answer is correct because calories are the substances used to provide energy in drinks and this question is a mathematical problem, not a question about energy."

This joke touched on the intersection between mathematics and philosophy. The mathematicians tried to answer the philosophers 'questions with precise calculations, but the philosophers' answers showed that the question itself was not about calculations, but about language and concepts. So the humor of this joke is that the philosopher uses a simple language to answer a complicated question, but the mathematician doesn't understand his answer.