Guess your age

[FLYING BANANA]

Three 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 happily crowed.....
'We were at your birthday party yesterday.'