Three mischievous old grannies were sitting on a bench outside a nursing home when an old grandpa walked by. One of the grannies shouted:
“Hey there! We bet we can tell you exactly how old you are!” 
The old man laughed and said,
“No way you can guess that, you crazy old ladies!”
One granny winked and said,
“Sure we can!
Just drop your pants and underwear, and we’ll tell you your exact age!”
The grandpa, feeling a little embarrassed but eager to prove them wrong, dropped his pants. 
The grannies inspected carefully — asked him to turn around twice, jump up and down a few times…
Then they all yelled out together:
“You’re 87 years old!” 
Shocked, the grandpa pulled up his pants and asked,
“How in the world did you guess that??” 
The grannies burst out laughing and said:
“We were at your birthday party yesterday!” 
