Grandpa and Little Johnny are sitting on a bench in the park.
Johnny asked, “Grandpa, are you going to take that new Viagra?”
Grandpa, caught off-guard, looks at him and says,
“No Johnny, I will not. “
“But Grandpa, why not?” asks little Johnny.
Grandpa replies,
“Well Johnny, because there is no sense in putting lead in your pencil if you have no one to write to. “
This joke is included in the Black Book of Jokes. You can order it from here.