Karen has finally forgiven Hank for his transgressions and they are back in the sack together. However, things aren't up to par for Karen. Hank is disturbed that she didn't have an orgasm, and wants to rectify that - but there is no time: they have been invited to luncheon at Felicia's house, and the surprising part is that Karen actually accepted.
Hank and Karen show up at the Koons' house to find that they'll be spending the afternoon with Felicia, Jill, and Jackie. The guests have a common interest - ripping on Hank, and Karen is relishing the derisive talk. One final guest arrives - it's Richard Bates, the professor that Hank had replaced, back from rehab. It's clear that he and Karen know each other, and Hank is anxious to know how. It turns out that Bates is the professor with whom Karen had an affair as an undergraduate! The afternoon discussion turns to reliving their heated relationship.
Meanwhile, Marcy and Charlie are having an open house. As Marcy tries to mobilize Charlie to get out of the house before potential buyers show up, she walks in on Charlie doing some girl on his bedroom floor. Later at lunch, she admits that she might be a little bit jealous. Before the conversation can get too deep, Marcy gets an interrupting call from the realtor - someone made an offer on their house!
Back at the house, Marcy and Charlie toast the sale of their house. They discuss all the good memories they have there - but they realize that they haven't christened one room in the house. So Charlie convinces Marcy to have sex in the powder room. During the act, they awkwardly lean against the sink, and the whole fixture collapses to the ground, water spraying everywhere. As Marcy helps Charlie up, she notices the butterfly tattoo with her name on her lower back. She is both sickened and touched.
Charlie hurts his back when the sink crashed, so he convalesces with some pain medicine on the couch. Marcy notices that the divorce papers have arrived. Charlie makes one last attempt to convince Marcy to stay. They hug in an acknowledgment, that things aren't going to get better between them.
At Felicia's luncheon, all of the women are fawning over Richard Bates' sensitivity, to Hank's dismay. All of a sudden, Stacey Koons shows up in a full Civil War General get-up, and challenges Hank to a duel. He has just returned from a re-enactment group and is quite drunk. Felicia, and the other women, encourage Hank to take him on.
Ten paces out, and Stacey draws his gun, which misfires. He waits for Hank to fire back, but he just stands there. Stacey's gun misfires again twice. Hank says he refuses to play along, when his gun goes off accidentally. Stacey charges Hank and tackles him to the ground, apologizes for his behavior and then punches him in the face.
Bates laughs at all of this, which offends Hank, given the impropriety of Bates' language used to discuss Karen all day. Then Bates really makes a low blow: he brags that he can still remember the sounds of Karen's orgasm. Hank decks him and the two men go down. Stacey jumps on top, and the three of them roll around on the grass wrestling.
After the men clean themselves off, the party comes to an end. Hank says goodbye to his flings, who seem easily distracted by Richard Bates' presence. Hank takes Karen back to bed, to finish up what they started that morning. At first he is concerned that she's all riled up from reliving her relationship with Bates - but it's Hank we're talking about - he gets over that really quickly.