Grandpa Tries Viagra

Grandpa and Grandma were visiting their kids overnight when Grandpa found a bottle of Viagra in his son's medicine cabinet.

He asked the son about using one of the pills but the son said, "I don't think you should take one, as they're very strong and very expensive."

"How much?" asked Grandpa.

"$10 a pill," answered the son.

"I don't care," said Grandpa, "I'd like to try one. I'll leave the money under your pillow as soon as I break this $50 bill."

The next morning, the son found $110 under his pillow.

He said to Grandpa, "I told you the pills were $10 not $110."

"I know," said Grandpa, "The hundred is from Grandma."