What do you mean, "you are old and have no knowledge at all"

It can be understood that you are old and have no knowledge at all, but jokes are a burden.

jokes bear the meaning of allusions. Once upon a time, there was a scholar who was almost seventy years old when his wife suddenly gave birth to a son. This son was born because he was so old, so he was named "Age". Soon after, another son was born, who, like a good reader, was named "learning". The next year, when he got another son, the scholar smiled awkwardly and said, "It's a joke to have a baby at such a big age." So he named it "joke".

When the three sons grew up with nothing to do, the scholar let them all go into the mountains to get firewood. When they came back, the scholar asked his wife, "Who's the three sons?" The wife replied, "I'm old, I have no knowledge at all, but I have a burden of jokes."