Randi is told the rules of the game. She'll have to convince her family that she's in love and will be getting married in 12 days. She meets her fiance Steve, who is of course the big fat obnoxious fiance of the show's title. What she doesn't know is that Steve is actually an actor paid to be as annoying as possible. Steve and Randi eat breakfast and go to a spa. The wedding invitations are mailed.

Steve and Randi visit a wedding planner and try on tuxedos and wedding dresses. Steve pretends to get emotional when he and Randi dance. The next day Randi gives Steve a list of things he needs to change, and they visit a sex therapist. Randi's best friend, Anna, visits the estate and Randi tells her she got engaged.

Anna meets Steve, Randi tries to do yoga with Steve, and Steve gets a makeover. Steve introduces Randi to his family, played by actors, and announces that they are engaged. Randi calls her family and gets them to agree to come and meet Steve.

The Coys arrive. Steve and Randi go to meet them, and Steve has a panic attack. Steve and the Coy family go on a short cruise where Steve acts like an intelligent, suave gentleman. The next day Steve is back to his normal obnoxious self. He and the Coys play croquet. They all eat outside and Randi tells them she and Steve are married. That night the Coys and the Williams meet each other at a luau. The Williams burp and the Coys don't like them. Randi and Steve make a toast and announce that they are getting married in 3 days.

The family is shocked by the news of the wedding in 3 days. The next day Randi talks to her parents and they agree to come to the wedding. Bobby doesn't like it, but will come. Patrick refuses to be a part of it. The day before the wedding Steve, Bruce, Jimmy, and Richard are fitted for tuxedos while Randi, Laura, Anna, and Catherine meet with the wedding planner, Jill. That night they have the wedding rehearsal and Jimmy makes a speech. Catherine goes to Melanie and Patrick and insists that they be part of the wedding.

On the day of the wedding it is raining. The Coy family is getting ready for the ceremony and Melanie is very upset with Randi. People start to arrive for the wedding. The ceremony starts. Patrick and Bobby wear kilts because of the Coys' Irish heritage. All of Randi's family comes, and no one objects. When the time comes for Steve to say ""I do"" he says he can't, and tells everyone it's not a real wedding. The Coys, except Bruce, storm off into the house. A producer gets them to come back. Steve explains to everyone what the show is really about, then reveals that he and his family are actually actors. He gives a speech about the Coys' love for each other and gives them checks: $500,000 for Randi, and $500,000 for the rest of her family. Randi's family forgives her, and they watch a clip from when Randi first met Steve.