The episode begins at the Coffee Shop, where Eileen invites Mordecai and Rigby to her Christmas-sweater party at her house for later that night. Mordecai is at first happy to share his first Christmas holiday with CJ, but when Eileen tells him and Rigby that Margaret is going to be there, Mordecai is horrifed. Believing that CJ will not react very well at seeing her, Mordecai panics and hurriedly leaves the Coffee Shop when Eileen tells him Margaret is on the way.
Later, Mordecai, Rigby, Muscle Man, and Hi-Fives are setting up decorations on the house. After Mordecai daydreams about a worst-case scenario between Margaret, CJ, and himself (causing them to crash off the house), Benson orders Mordecai and Rigby to take a package to the Post Office. Rigby declines, as he has to wrap his Christmas gift for Eileen, leaving Mordecai to the task. Hesitant over possibly seeing Margaret on the way, he reluctantly goes.
As he opens the door to the Post Office, reassuring himself all the way there he won't see Margaret, Margaret ends up on the other side of the door. After an awkward re-acquaintance (mainly because of Mordecai), Mordecai fabricates a reason to run away from her (pulling "a Mordecai" in Rigby's words).
Back at the house, Rigby is trying to wrap Eileen's present. Mordecai enters and tells Rigby about blowing it with seeing Margaret again. As Mordecai ponders whether he should go at all, CJ calls, asking him about the party that night. When Mordecai struggles to answer CJ, Rigby answers for him and smacks Mordecai back into shape. Rigby's last piece of advise: reasoning that this'll be the last time he sees Margaret since she's only visiting for the holidays, "Dude, just go to the party."
That night, Eileen's party is in full swing. Mordecai and Rigby show up, where Eileen takes their coats to her spare room (now that Joanne left). Rigby presents Eileen his gift: a mistletoe disco ball. Inside the party, CJ shows up, noticing Mordecai's increasingly sweaty and nervous manner. As Mordecai denies anything wrong, Margaret walks into the party, leaving Mordecai to hastily lead CJ away from her. At the fancy soda table, Margaret approaches Mordecai and CJ, wanting to speak to Mordecai. However, when she introduces herself to CJ, Mordecai awkwardly reminds them of the events of "Yes Dude Yes" (trying to play off that they've met before.) Margaret leaves following an awkward silence. CJ, understanding now that Margaret's the reason for Mordecai to be acting the way he is, wonders if he still feels anything for Margaret. Mordecai, finally calm enough, explains that since they broke up, he's been happy with CJ, that he doesn't feel anything for Margaret anymore, and that he wants to be there with her. CJ kisses him reassuringly, saying "that's all I needed to know".
With the weight of his worries gone, everyone including Mordecai is enjoying the party now. After some time, CJ leaves to use the restroom (to wait in the long line). When the mistletoe disco ball begins working, the couples in the party share a kiss; namely, Muscle Man and Starla, Hi-Fives and Celia. Rigby, being egged on by Mordecai, kisses Eileen on the cheek.
Mordecai, trying to stay in the moment, leaves to find CJ. Unsuccessful, Mordecai runs into Margaret, causing him to panic and unwittingly cause a chain reaction ending with the disco ball projecting Margaret across the room. Finally, after some pleading and kind words from Margaret, Mordecai opens up, explaining how things are different now that he's been dating CJ; things were rough following the breakup, but CJ has made him happier, and that she's good for him. Margaret, understanding, reassures him that she never expected him to wait for her and he deserves to be happy. With the hatchet finally buried, Margaret and Mordecai share a hug to signify a return to their once friendly manner, exchanging a "Merry Christmas". However, Mordecai begins imagining the height of their relationship, starting with their activities in "Steak Me Amadeus" and ending in the kiss they shared in "Meteor Moves" . When the flashback lifts, Mordecai and Margaret are seen kissing.
Immediately reprehensive, Mordecai and Margaret apologize to each other. Suddenly, a faint "Mordecai?" is heard. They turn to see CJ, tears welling in her eyes and thunder storming before running out of the house. Mordecai desperately races after her, but to no avail as she drives off. Seeking to call her, Mordecai searches for his phone and runs back to the house. Entering the spare room where Eileen left their coats, he finds boxes of Margaret's personal items inside. Here, Eileen reveals that Margaret is her new roommate as she'll finish her degree at the news station, before leaving hastily. The episode closes on a cliffhanger as Margaret looks on to the distraught Mordecai.
|J.G. Quintel|| Mordecai|
Hi Five Ghost
|William Salyers|| Rigby|
|Linda Cardellini||Cloudy J|
|Courtenay Taylor|| Starla|
|Cartoon Network Studios|
|"A Space Ghost Christmas" • "George and Junior's Christmas Spectacular" • "Dexter Vs. Santa's Claws" • "Twas the Night" • "Happy Baboon Holidays" • "Fa-La-La-La-Ed" • A Johnny Bravo Christmas • 'Twas the Fight Before Christmas • "Christmas Con Carne" • Ed, Edd n Eddy's Jingle Jingle Jangle • "Christmas Evil" • Billy & Mandy Save Christmas • "A Lost Claus" • "Operation: N.A.U.G.H.T.Y." • "Have Yourself a Joyful Little Animas" • "Kamp Kringle" • "Merry Christmas" • "The Class of 3000 Christmas Special" • "Hey, Hey It's Knishmas!" • "Low Tidings" • "Holly Jolly Secrets" • "The Regular Show Christmas Special" • "Christmas" • "Uncle Grandpa Christmas Special" • "Merry Christmas Mordecai" • "Secret Santa" • "Merry Moochmas" • "Christmas Parties" • "Chill Out" • "Christmas in Space"|