Little Timmy is playing on the street when he spots a package of Viagra pills. Being a boy of the world, he immediately recognizes the possibilities and approaches his daddy, "Dad, I just found these, and I'm willing to sell them to you for $100 straight."
"Son, well, while this is a very good offer, I'm in perfect physical health and not currently needing those. Tell you what, go ask Grandpa."
So Timmy walks over and asks his grandfather, "Gramps, I will sell you this package of Viagra for $100."
"Oh, thanks Timmy, but are you sure these will work?" asked his grandfather.
"Gee, I don't know," said Timmy. "But they do look like the ones that were shown on TV!"
"Tell you what, Timmy, I'll try them tonight and if they work okay, I'll give you the money tomorrow."
The next morning, Timmy visits his grandfather again, and Gramps hands over $500 without hesitation. Timmy is perplexed, "But Gramps, I thought we agreed on $100."
"That's okay, Timmy, keep it," replied the grandfather. "The rest is from Grandma!"