Three old mischievous grandmas were sitting on a bench outside  a nursing
home. An old grandpa walked by, and one of the old grandmas yelled out  saying,
"We bet we can tell exactly how old you are."

The old man said,  "There aint no way you can guess it, you old fools."

One of the ornery  grandmas said,

"Sure we can! Just drop your under shorts and we can tell  your exact age."

Embarrassed just a little, he dropped his  drawers.

The grandmas stared at him for a while, asked him to turn around  a couple of
times, asked him to jump up and down for a little while and then  they all
piped up and said, "Youre 84 years old!"


"How in the world  did you guess?!?"

The ornery old grandmas snickered and laughed. Slapping  their knees and
grinning from ear to ear, all three happily yelled in  unison,

"Because we were at your birthday party  yesterday