Some jokes about turning 40 years old include jokes about not being able to move as fast as in past years and jokes about hearing, hair and vision loss. One joke about turning 40 says that in every 40-year-old person there is a 20-year-old wondering what happened.
Another joke about turning 40 is that a person knows he is over 40 when he puts a rubber mat in the bath tub. People turning 40 often joke that 40 is the age when no babysitters address the older person by her first name.
One 40-year old quipped that, because the 40s are the "new 20s," he spends his time eating cold spaghetti and playing on the computer. Another 40-year old said that, even though she is 40, she still has moves, but she just can't make them as quickly.
When a person turns 40, he might joke that he loses his car keys and then loses the keys again only a few minutes later. Another 40-something person adds that now that he's 40 years old, he still feels like a 20-year-old when he wakes up in the morning, but there is never a 20-year-old around.
Another 40-year-old joke is about two turtles that celebrated their 40th birthdays together. One of the turtles, Fred, left to get ice cream to celebrate, but because the turtle was 40 years old, he could no longer walk as fast as he used to. When Fred didn't come back after a couple of days, one of the friends joked that Fred couldn't walk quickly anymore. But because Fred was so slow, he had not even made it to the door. Fred quipped back that he wouldn't go get the ice cream because he heard the other turtles talking about him behind his back.