"Dr. Yap" is the sixth episode in Season 2, being the nineteenth episode overall.
As the family is serving at the restaurant, Gayle stops by for a visit on her trip without calling them ahead of time. She gives the kids presents, and gives Gene a jawbreaker. Louise gets jealous, so she decides to do a challenge for it, with Tina as the referee. Gayle drives to the dentist's office to pick up Bob, after going under a procedure with heavy medication. With Bob still hallucinating from the drugs, he hallucinates Gayle for his wife. On the way back, he kisses Gayle in the car, not realizing his mistake.
When Bob wakes up, Gayle tells him about what happened. She tells him that they made love orally, much to Bob's surprise. Gayle tries to get Bob not to tell about what happened to Linda, but he decides to do it anyway. When Linda is told about the incident, she is happy to hear that Gayle has fallen in love again, as she tells about how she dated somebody back in her youth, Gayle fell in love with her boyfriend, and later found another guy.
After finding out, Bob decides to bring the family up to Dr. Yap's cabin, hoping to get Gayle to fall in love with the dentist. Dr. Yap uses weak methods to get Gayle to love him, learning from a video tape. While skiing, Bob keeps being chase by Gayle. She finally traps him, breaking his tooth, and gets on top of him. Linda finds the two in this position, and mistakes Bob for cheating on her. She slaps him on the cheek, as Bob tries to tell them the incident.
Back at the cabin, Dr. Yap pulls Bob's tooth out while Linda is still a bit antsy from what happened. Linda decides to "steal" Dr. Yap, and Gayle pronounces that she has been in love with him the whole time. In the end, Gayle is no longer finding love in Bob, and Linda comes to her senses with Bob. In the end, Tina is shown watching Dr. Yap's tape on getting love.