Gentlemen: I shall never shave, for the same reason that I started a beard, and for the reason my father started his. I remember standing at his side, when I was five, while he was shaving for the last time. “Father,” I asked, “Why do you shave?” He stood there for a full minute and finally looked down at me. “Why the hell do I?” he said.

George Bernard Shaw (1856–1950) Irish playwright and critic
(Attributed)

Postcard response when invited by an electric razor company to shave off his beard with their product.Variant:
  • "I was about five at the time, and I was standing at my father's knee whilst he was shaving. I said to him, 'Daddy, why do you shave?' He looked at me in silence, for a full minute, before throwing the razor out of the window, saying, 'Why the hell do I?' He never did again."