And old man and his girlfriend

And old man and his girlfriend

meet to sit on the same park bench every day, and every day, she holds his dick in her hand while they talk, a small pleasure he still enjoys. This goes on for years, but one day he's already at the bench with another old lady, who is holding his junk, when his old flame gets there. Hurt, she composes herself and asks "ok, so what's she got that I ain't got?"
He looks at her and says "Parkinson's".