Grandpa and grandma were living with their son and daughter-in-law.

Grandpa noticed that his son had a bottle of Viagra and asked if he could have one.

His son said, "Dad, I don't think you should take one they're very strong and expensive."

Grandpa said, "I know -- but I want to try one. How much are they?"

His son said, "They're $10 each."

Grandpa only had a $50 bill but he said he was going to the bank and would leave $10 under his son's pillow that night.

The next morning his son found $110 under his pillow and said "Dad, I told you it was only $10 -- there's $110 under my pillow!"

Grandpa said, "That's okay, -- the other $100 is from Grandma!"