The gang is still in the Little White Chapel in Las Vegas. Monica and Chandler are about to get married when a very drunk Ross and Rachel walk out of the chapel. Joey and Phoebe arrive to stop them, but are too late.
Ross and Rachel wake up hungover with fuzzy memories of the previous night and drawings all over their faces.
Joey and Phoebe arrive at breakfast and Joey announces that he's returning to NYC. Monica and Chandler join them. At the buffet, Chandler discusses the previous evening with Joey. He realizes he's not ready to marry Monica. Meanwhile, Monica has a similar conversation with Phoebe. Ross and Rachel finally arrive, not realizing that they got married. Their friends tell them and suddenly they realize that they did get married. The gang teases Ross about his frequent divorces.
Back in the hotel, Chandler and Monica awkwardly discuss their relationship. Both continue to remind one another that they love each other while delicately trying to tell the other that they aren't ready. They agree that if she rolls an "8" then they'll get married and she does. However they agree that it wasn't a hard 8 so it's not a big enough sign. They head to the elevator, the doors open, and a minister is in the elevator.
Joey and Phoebe are making the trip back to New York in the taxi cab. Phoebe is driving and Joey keeps falling asleep so she insists that he drive. Then she goes to sleep and he drives. He is falling asleep as he drives and the next thing you know, Phoebe and Joey are in the backseat asleep and a hitchhiker is driving the car.
At Central Perk Rachel is having coffee, Ross walks in and they sit down to talk. He tells her he doesn't want to annul the marriage. Rachel assumes that he's kidding, but it turns out that he's not. He tells her he can't have three failed marriages. Ross tries to convince her that it's really not a big deal and is just an issue of paperwork. Rachel tries to show him that it's a ridiculous ideal.
Chandler and Monica are returning to their apartment from the airport. Monica is limping and Chandler is helping her because a boy on the airplane kicked her after she pulled his hair in a fight over snacks. Chandler picks her up to help her into the apartment, simulating newlyweds crossing the threshold, and they both insist that this doesn't mean anything.
Phoebe is now driving the cab, arguing with Joey about the hitchhiker. Phoebe then plays the license plate game with the hitchhiker.
Ross again tries to convince Rachel to stay married by offering to register for gifts and allow her to keep them all. He tries to tell her that this is just a difference of opinion that occurs regularly in a marriage. Rachel insists this is not a marriage, it's the world's worst hangover.
The hitchhiker arrives at this train stop and gets out of the car. He and Phoebe have become friends and she give shim her number. Joey tries to make friends with Phoebe again, singing to her as she drives. They finally make up and play "20 Questions."
Back in the apartment, Rachel is arranging flowers and accidentally throws them back. Monica catches them. Chandler asks if all of these signs mean they should go ahead and get married, but both admit they aren't ready. Monica sends Chandler back to his apartment. He leaves, but quickly returns, asking her about possibly unpacking at her place. Monica doesn't catch on and after a few attempts, he asks if she'd like to live together. They both agree. She gives him a key and he leaves to reenter using the key. The key breaks in the lock and both insist this isn't a sign against living together.
Ross enters Central Perk and meets Phoebe and Rachel. Rachel asks if he completed the annulment, Ross says yes, but then tells Phoebe that in actuality, he and Rachel are still married.
Chandler is still trying to open the apartment door. Joey tries quickly to use a tool and then busts the door down by running into it.