“Opportunity only knocks once, but temptation leans on the doorbell.”

“If opportunity doesn't knock, build a door”

“When opportunity knocks, We are either out or sleeping in.”

“A pessimist is somebody who complains about the noise when opportunity knocks.”

“No, you don’t need to help me. But if you don’t, there’s nothing stopping me from calling you up again and again, now that I know you can’t kill me. Think of it as me leaning against your Heavenly doorbell… forever.”

“When the doorbell rings at three in the morning, it's never good news.”

“The more Susan waited, the more the doorbell didn't ring. Or the phone.”

“Democracy means that if the doorbell rings in the early hours, it is likely to be the milkman.”

“One only dies once, and if one does not die well, a good opportunity is lost and will not present itself again.”

“[After the doorbell rings, right before Secretariat appears] Who's that at the door?!”