Lol, both of those last two!

Three mischievous old Grandmas were sitting on a bench outside a nursing home

When an old Grandpa John, walked by.

And the one old granny yelled out saying, "We bet we can tell exactly how old you are."

John said, "There is no way you can guess it, you old fools."

The second old lady said, "Sure we can! - Just drop your pants and under shorts and we can tell your exact age."

Embarrassed just a little, but anxious to prove they couldn't do it, John dropped his drawers.

One of the old aunties asked him to first turn around a couple of times and to jump up and down several times. Then the three of them all piped up and said, "You're 87 years old!"

Standing with his pants down around his ankles, John asked, "How in the world did you guess?"

Slapping their knees and grinning from ear to ear, all the old girls happily yelled in unison...

"We were at your birthday party yesterday!"