Two male classmates discuss how Marcia "drives them crazy" with her appearance with one saying "she's harder to get into than a Pear Jam concert"
There's a scene of Alice in a vibrating recliner and she remarks "And I thought Sam had magic fingers." Could come across as an innuendo but flies over the naive Brady's heads as they just laugh.
The Brady's neighbor's wife (who in prior comments" has expressed her interest in the 3 older Brady males) suggest that Greg and Peter come inside and help her make a sandwich when they are finished with their tasks. Could have literal meaning, but given prior comments, it most likely doesn't and has a double meaning.
It is heavily implied that Marcia's best friend from school, Noreen, is a lesbian. The girl clearly has a crush on Marcia, and they sleep in the same bed while having a sleepover, with only their heads showing. Everything else is covered by blankets. Noreen even rubs her leg against Marcia's under the covers. Of course, throughout the movie, Marcia is completely unaware of Noreen's feelings for her, highlighting the naivety and innocence of the entire Brady family.
Marcia rejects her date's sexual advances while they are sitting in a car. She says that she's not the kind of girl who goes to third base, and as a result, he makes her get out of the car.
When Marcia is afraid her date won't want to take her to the dance because of her injured nose, he says "Don't worry, it's not your nose I'm after". A minute later, when Mrs. Brady asks him if he has "protection" (against the rain), he says "Sure I do" and describes having "assorted colors and textures." Both lines have sexual implications, although it flies right over Marcia's head as well as her parents'. They obviously don't get it.
Peter faints in health class when the teacher is explaining about the female reproductive system and menstruation/ovulation, because he can't handle the information. Later in the movie, he bumps into the same teacher and accidentally puts his hands on her breasts to catch himself, making him faint again.
A female neighbor of the Bradys' says to Cindy, "Next Christmas, tell your daddy I'd be more than happy to wrap his package." This obviously has sexual undertones, but Cindy happily agrees to deliver the message to her dad, and then she does. Mr. and Mrs. Brady don't get it, either.
The same female neighbor of the Bradys' tells Greg when he comes over, "You sure have been getting bigger" and "You're almost as big as your dad"; both could be sexual innuendos.