Old man goes back to the doctor.
"Have you been taking those Viagra as I've prescribed? A FULL tablet"
"Nope," the old man replies, "been breakin' `em in quarters. At that price they last longer."
"A quarter tablet won't be enough to enable you to engage in intercourse" scolds the doc.
"I'm 95 years old. Don't want no intreecourse. Just need enough to quit pissin' on my shoes"