Okay kiddo, so there is a festival called Vessantara where people celebrate a story from a long time ago about a man named Prince Vessantara.
Prince Vessantara was really kind and generous. He gave away everything he had, even his elephants and his most precious possession - a magical wish-granting gem - to people who needed them more than he did.
One day, he gave all his belongings, including his wife and kids, to some people who really needed them. This made some people very angry and they said Prince Vessantara was giving too much away.
So, they forced him and his family to leave their home and live in the forest. After many hardships and challenges, Prince Vessantara proved that he was still kind and generous, even in the toughest of situations.
The story has a happy ending because the gods in the sky saw how good Prince Vessantara was and gave him back his stuff, including his family.
Now, every year people celebrate this story by dressing up, making offerings, and doing good deeds to remind themselves to be kind and generous, just like Prince Vessantara.