Claire feels inadequate after an old friend visits; Jay has an unsettling moment in the locker room with Cameron; Mitchell helps Gloria with legal issues.
Phil and Claire decide to break with their usual Valentine's dinner date and opt for a role play excursion; Jay and Gloria clash over ideas for romance.
Chandler and Ross fight over ownership of a joke published in Playboy; a broke Joey starts working at Central Perk; Phoebe's wayward remark causes trouble.
After her father cuts her off, Rachel's sister, Jill, comes to town and goes on a date with Ross; Joey gets in trouble for giving female customers free food.
The conclusion of the "what if" episode shows Ross having a threesome with Susan and Carol, Rachel kissing Joey and Monica and Chandler hooking up regardless.
Ross ponders dating a student who is smitten with him, even though it could cost him his job; Rachel moves in with Joey after her apartment burns down.
Joey's fridge is broken and he tries to cajole his friends into helping him buy a new one; Phoebe, Monica and Chandler compete to get Rachel a date for a ball.
Ross asks his friends to keep him company when he meets Elizabeth's dad for the first time; Joey may get fired when he fights with C.H.E.E.S.E's operator.
Chandler tries to make Monica think he doesn't want to get married in an attempt to surprise her with the ring; Richard proposes to Monica at her work.
Planning for the wedding begins; Phoebe moves in with Ross, bringing her massage parlor with her; Monica's parents spend the wedding money on a beach house.
A geek-turned-lethal CIA agent recruits an accountant who used to be the most popular athlete in his high school to save the U.S. spy satellite system.
Sheldon tries to connect with Amy's father but is later forced to bond with her mother; Raj and Anu explore the physical aspects of their relationship.
A gorilla is exposed to a chemical from a secret genetic experiment, which causes the gorilla, a wolf and a crocodile to grow to enormous size and wreak havoc.