Cindy comes home upset and refuses to talk. Eventually she tells her parents that kids at school, especially Buddy Hinton, tease her because of her lisp. Carol tells Cindy that she had a lisp when she was a girl. Mike and Carol come up with ideas to help Cindy get over her lisp and have her practice some tongue twisters with lots of s's. Under encouragement from her parents and siblings, Cindy starts doing well with the tongue twisters.
But Buddy catches Cindy while she is practicing and starts his teasing over her lisp: "baby talk, baby talk, it's a wonder you can talk!" Peter intervenes and tells Buddy to stop teasing Cindy. Buddy tries to pick a fight with Peter. When Peter doesn't fight, Buddy calls him a scaredy cat and other synonyms for a coward. Now Peter is the one who comes home upset. Worse, his brothers heard what happened because Buddy spread the story all over the school. When Mike hears, he tells Peter that reasoning with Buddy is better than fighting. But when Peter tries reasoning with Buddy, all he gets is a black eye.
Mike tries talking to Mr Hinton about Buddy's bullying, but Mr Hinton does not care. He tells Mike to "buzz off" and even threatens to fight him. When Mike's own words to Peter about reasoning echo in his mind, he says, "Oh, shut up!" to it. Mike now realizes that Buddy is a bully because his father is. He tells Carol that from now on, Peter has his permission to defend himself. Carol says women are different and she will go to Mrs Hinton, talk calmly and sort everything out. But she too gets nowhere because Mrs Hinton is a complacent, weak-willed woman who does not stand up to her husband and gets told to "buzz off" whenever she tries to talk to him about Buddy's bullying. Now it is Carol's turn to say "oh, shut up!" when her own words echo in her mind.
Carol and Mike now agree that Peter has the right to defend himself. Mike tells Peter that he should still try reasoning first, but if that does not work, he can defend himself. Peter is delighted with the change in advice, but he is scared because he has never been a good fighter. So the family start giving Peter boxing lessons. Meanwhile, Cindy has kept up with her tongue twisters and is now confident she can handle her lisp.
At school, Peter is puzzled as to why there are a big crowd of kids behind them. Cindy says she might have mentioned there would be a fight with Buddy. And Buddy is waiting for "baby talk and the chicken." Peter, following Mike's advice, tries reasoning first. When that fails, he puts up his fists for the fight, which ends with a left hook going into Buddy's face. Buddy gets a nasty shock and starts crying. Peter is also shocked at how hurt Buddy is and apologizes. The punch loosened one of Buddy's teeth, and now he is the one with the lisp. Cindy fires the line "baby talk, baby talk, it's a wonder you can talk!" back at him. Buddy runs off in tears. The kids all laugh, but Peter silences them, saying it is not funny.
Buddy calls around at the Brady house. He asks if he can borrow Cindy's tongue twister book to help with his own lisp. When the Brady parents ask Buddy what he has learnt, he says he has learnt that Peter has a good left hook. Things are now more friendly between Buddy and the Bradys.