What is the experience of laughing on a serious occasion?

In primary school, I played at home with my classmates and pretended to cook with checkers. My classmate cooks very carefully. Suddenly, I felt as if I had jumped. I think it's really shameful for this eraser to cook with checkers. Then I rolled down from the bed and smiled for three minutes. My classmate, my mother and my classmate's mother all came to see me in surprise.