“I wonder if rooms in an insane asylum have Do Not Disturb signs for the doors. I should hope not, because knock or no knock, every occupant in those rooms is already disturbed.”

“I’m a door-to-door salesman. I sell doors. If I can’t knock on yours, because you don’t have a door to knock on, I know you’ll be interested in what I’m selling.”

“If I tell you I want to be a door-to-door salesman, don’t knock it.
”

“The first door in the hall leads to youth, the second door leads to middle age, and the third door leads to the bathroom. But knock first, because I think grandpa’s in there.”

“I never got to call myself a door-to-door salesman, because, regrettably, I only ever went to one door. But one day I just might knock on another door, to be able to proudly say that I was once a door-to-door salesman.”

“I can draw like it’s nobody’s business. I use my door as a canvas, so don’t knock, because it’s nobody’s business.”

“I just baked a cake in the shape of a door. Somebody’s knocking now, so let me get that.”