What joke can make people laugh after watching it several times?

(of men and women in love) meet in secret.

One day, Wang Yun invited Dong Zhuo to drink at home. During the dinner, The Story Of Diu Sim, Yun3' s daughter, was in charge of pouring wine. Dong Zhuo and The Story Of Diu Sim are flirting, but they are eager for each other. When he left, The Story Of Diu Sim knocked on Dong Zhuo's head three times, and then left with his hand behind his back. In the middle of the night, Dong Zhuo entered from the back door of Wang Yungu's house and came to The Story Of Diu Sim's room. The door opened automatically. Dong Zhuo walked in the door for a while and saw two doors. It says "married" on one side and "unmarried" on the other. Dong Zhuo walked in through the "unmarried" door. After a short walk, there are two more doors at the end of the corridor, which say "experienced" and "inexperienced" Dong Zhuo walked on through the "inexperienced" door and came to the end of the corridor, where there were also two doors. It says "10 cm above" and "10 cm below". Dong Zhuo opened the door of "less than 10 cm" and went out to the road. ...