I recall an episode early on in the series when Jack was returning to the apartment carrying two large bags of groceries so he didn't have any available hands to open the door or ring the door bell. So he pressed his nose on the door bell to ring it repeatedly.

Janet and Chrissy then opened the door but Jack was unaware and they observed him continuously ringing the bell with his nose.

What episode was that?

that was from "THE PARTY IS OVER" where Mr. Roper doesn't let the kids have their party and Mrs. Roper leaves him!:)