Four mischievous Grandmas were sitting at a table in a nursing home when an old Grandpa walked in.
One of the old Grandma's yelled out,
'We bet we can tell exactly how old you are.'
The old man said, 'There ain't no way you can guess it, you old fools.'
One of the old Grandmas said, 'Sure we certainly can!
Just drop your pants and underpants and we can tell your exact age.'
Somewhat embarrassed, but anxious to prove the old
Grannies wrong, he dropped his drawers.
The Grandmas asked him to turn around a couple of times and to jump up and down several times. Then after a short pause, in unison they all piped up and said,
'You're 87 years old!'
Standing with his pants down around his ankles, the old gent asked, 'How in the world did you guess?'
Slapping their knees and almost falling about with laughter, all four ladies happily yelled in unison-
'Cos we were at your birthday party yesterday!'