Brad and Mary find a porn magazine that starts them exploring sexually with each other. Their mother finds out and decides to help them back to the correct path.
Greg and Peter have a little secret: They like to peek at their stepsister Marcia when she's in the bathroom. One night their peeking leads to more -- a lot more, which, it turns out, Marcia is not all that upset about. In fact, she helps her stepbrothers get it on with another of the blonde Brady girls, Jan. (Celeste's score: 10, 9, 9: "Stranger things have happened on American
sitcoms.")