Three mischievous old Grandmas were sitting on a bench outside the nursing  home when an old Grandpa walked by. One of the old Grandmas yelled  out,  'Hey, we bet we can tell exactly how old you  are!'

The old man said, 'There is no way you can guess my  age!

One of the Grandmas said, 'Sure we can! Just drop your  pants and undershorts and we can tell your exact age.'

Embarrassed, but anxious to prove they couldn't do it, he dropped his drawers.

The Grandmas asked him to first turn around a  couple of times and then jump up and down several times.

Determined to prove them wrong, he did it.

Then they all said in unison, 'You're 87 years old!'

Standing with his pants down around his ankles, the old gent asked, 'How in the world did you guess my  age?'

Slapping their knees, high fiving and grinning from ear to  ear, the three old ladies again happily crowed in  unison, 'We were at your birthday party yesterday.'