Grandpa noticed a bottle of Viagra in his son’s medicine cabinet and asked if he could try one.

The son replied, “I don’t think you should take one, Dad — they’re very strong and very expensive.”

Grandpa asked, “How much?”

“Ten dollars per pill,” answered the son.

Grandpa didn’t mind. “I’d still like to try one,” he said, “and before we leave in the morning, I’ll leave the money under the pillow.”

The next morning, the son found $110 under the pillow. He called Grandpa and said, “I told you each pill was $10, not $110.”

Grandpa chuckled and replied, “I know. The hundred is from Grandma!”