Zhai Jing wanted to say that he wasn't afraid.
When he was young, his family was poor. To save some rent, his mother had brought him to live in the countryside for two years.
There wasn't much in the countryside except for vegetation, insects, and snakes. Especially in March and April every year, animals that had hibernated for a few months would run out to find food and let out the wind when spring was warm. Therefore, snakes could occasionally be seen in the wild.
At that time, the firefighting wasn't as good as it was now. The villagers weren't so afraid of snakes. Some brave children would even join forces to catch snakes and sell them for money.
Zhai Jing's family was short of money too, so he had followed them to catch the snakes a few times. Later on, he only stopped because his mother was worried that he would be bitten by a snake.