Here is a classic gerontology joke
Man's first visit with a new doctor
Dr: So when did your father die?
Patient: Who said my father died? He's 68 and runs the Boston Marathon every year.
Dr: Oh, sorry. So when did your grandfather die?
Patient: Who said my grandfather died? He's 89 and plays rugby every second night and presses 250 lbs at the gym.
Dr: Oh, my mistake...So when did your great grandfather die?
Patient: Who said my great grandfather died? He's 108 and he just got married last week.
Dr: 108...that's amazing! Why in the world did he want to get married?
Patient: Who said he wanted to get married?