What are some jokes that people of a certain age can understand?

Three women are talking about how inconvenient it is to be old.

"Sometimes," said a lady, "when I come to the refrigerator, I can't remember whether I want to put things in or just take them out."

"That's nothing," said another woman. "Sometimes I stand at the bottom of the stairs in a daze, not knowing whether to go up or come down directly from above."

"God," said the third woman, "I don't have those problems." As he spoke, he knocked on the desktop. "Oh, someone is knocking at the door." Said, and got up and walked to the door.