Chandler walks across the hall to the girls' apartment right as Rachel walks out of the shower topless. Later, in revenge, she tries to find a way to walk in on him in the shower, but walks in on Joey instead. So Joey tries to get revenge on Rachel, but walks in on Monica instead.
Also, Joey's dad is in town for work and staying with him and Chandler for a few days. Joey is horrified to accidentally find out his father is having an affair, and then is even more horrified to find out his mother knows about it (but pretends to be clueless) and doesn't care. She figures it's not ideal, but in the meantime he treats her nicer than he used to in order to try and keep her from getting suspicious. So she gets annoyed at Joey, thinking that now that his dad is aware that she knows, he'll stop trying to hide it with his romantic gestures to her. Tying it together with the main plot, Monica accidentally walks in on Joey's father in the shower when trying to get revenge on Joey.
Meanwhile, Phoebe is dating Roger, a psychologist who nobody else in the group likes because he continually over-analyzes them. They end up breaking up, once she informs him that her friends don't like the way he picks them apart, and he responds with scathing criticism of all their personalities and of the group's dynamics.
Tropes
- Bad Liar: Joey's mother says she long ago figured out the affair because Joey Sr. came up with absolutely laughable cover stories.Gloria: Your father is no James Bond. You should've heard some of his cover stories. "I'm sleeping over at my accountant's", (she shrugs) I mean, what is that? Please!
- Buffy Speak: Phoebe tells Roger that her friends "Have a liking problem with you, in that they don't."
- Does This Remind You of Anything?: The gang discuss dealing with parents in similar terms to how parents commonly discuss dealing with kids.
- Dope Slap: Joey's mother gives him one of these for trying to put an end to the affair.
- Escalating War: The series of "get back at the person who saw Character X naked in the shower" attempts.
- Everyone Has Standards: Joey is disturbed by the idea of being unfaithful to one's spouse, feeling that is a sacred commitment.
- Freudian Excuse: Part of what causes Roger to be so grating to the gang is how he psychoanalyzes various quirks and correctly deduces various items stemming from childhood issues, such as Chandler using humor as a defense mechanism after his parents got divorced.
- Friendship Moment: When Joey worries that he'd take after his father and cheat on a wife, Chandler assures him that won't happen.
- Gilligan Cut: Ross says that Roger is not so bad. Cut to him angry at Roger for suggesting that he married Carol while subconsciously knowing she was a lesbian.
- Go to Your Room!: A reversed version. After finding out about his dad's affair, Joey insists that they stay at his apartment so they won't "be doing stuff" at a hotel. When his dad tries to object, Joey tells him to "go to my room!"
- Going Commando: Averted. While having to share a bed due to the above, Chandler insists on Joey wearing underwear and doesn't want to hear any of his complaining about how uncomfortable it is.
- Happily Married: To Joey's disbelief, the ongoing affair has actually strengthened his parents' marriage. Gloria attributes Joey Sr. becoming more attentive out of guilt.
- Hypocritical Humor: Ross says they're all mature adults here and that there is only one appropriate solution: Rachel seeing Chandler's "pee-pee" would make things even.
- Innocently Insensitive:
- Mr. Tribbiani tries to be friendly with the gang but keeps accidentally choosing topics they'd rather not talk about.
- Roger himself too, he's a nice guy, just really intrusive over-analyzing the gang without asking and judging from his last speech he's got a few issues with rejection himself he doesn't handle well.
- The Mistress: Joey finds out that his dad has been seeing another woman, who explicitly refers to herself as being this.
- Modesty Towel: Rachel only has hers wrapped around her waist because she believes she's home alone, which is how Chandler ends up seeing her breasts.
- My Eyes Are Up Here: Rachel catches Chandler staring at her chest.Rachel: Why can't parents just stay parents? Why do they have to become people? Why do they have- [notices Chandler] Why... can't you stop staring at my breasts?
Chandler: [still staring] What? [looks up] What? - Naked People Are Funny: The whole point of the titular plot, where characters keep attempting to "accidentally" walk in on each other in the shower.
- Noodle Incident: According to Joey, his sister Tina got slapped with a restraining order by her husband.
- Only Sane Man: In light of his father having an affair, his mother pretending not to know about it, and his sister getting hit with a restraining order by her own husband, Joey turns out to be this to his family. He also avoids getting sucked into Roger's analysis, which his friends failed to do.
- Open Mouth, Insert Foot: Roger floats the idea that Ross subconsciously knew Carol was a lesbian all along and self-sabotaged by marrying her so that Monica would look better to their parents.Ross: That's ridiculous. I don't feel guilty for her failures.
- Parents as People: Not only is Joey's father having an affair, his mother prefers it that way because the shame is making him be nicer to her.
- Phrase Catcher: Everyone, even Phoebe ultimately, sums up their reactions to Roger by stating "I hate that guy!"
- Plot-Inciting Infidelity: Joey's plotline kicks off when he discovers his father is cheating on his wife.
- Secret Secret-Keeper: Joey's mom knows all about the affair, not that it was hard to figure out. Joey is perplexed by how she pretends to not know.
- Sherlock Scan: Roger is able to tell that Chandler's parents divorced before he was a teenager.
- Shower of Awkward: Chandler accidentally sees Rachel topless as she exits the shower. Rachel then tries to walk in on Chandler as payback but gets Joey instead. Joey then tries to get even by walking in on Rachel but gets Monica. Monica then tries to catch Joey, but instead sees Joey's dad, bringing the Zany Scheme Chicken to a screeching halt. Notably, Joey's father is completely unfazed.
- Trauma Button: In trying to catch up with the group, Joey Sr. accidentally references one of Phoebe's failed relationships and asks Ross how Carol is. Desperate, he suggests Chandler say something funny, which Chandler's reluctant to after talking to Roger.
- Unusual Euphemism: In response to the phrase "Tit for tat", Chandler says he's not letting Rachel see his "tat".
- What the Hell, Hero?: Rachel berates Chandler for accidentally seeing her topless. He apologizes, as well as points out how open the weave she's covering herself with is.
