"#HappyHolograms" is the tenth and final episode of Season Eighteen, and the 257th overall episode of South Park. It aired on December 10, 2014.
Still burning over Ike calling him a Grandpa, Kyle teams up with some heavy hitters in the entertainment industry to create the most extravagant televised Holiday Spectacular ever. He’s sure that this event will be just the thing to bring families together again. Meanwhile, multiple holograms are still on the loose in South Park.
The episode begins with Kyle narrating what's been happening recently. He talks about trending, commentators, and how his family is scattered, and how the living rooms are dying, so he starts a new trend, #savethelivingroom. Then, Bill Cosby comes in to see Kyle and he plans to use this trend on a big holiday special, airing this weekend. Kyle agrees, but as soon as he closes the door, Bill Cosby is revealed to be a hologram.
Meanwhile, Randy & Sharon talk with Sergeant Yates about copying other people, and he reveals to the whole police station that he's Lorde. Suddenly, Adams bursts into the room, telling Yates that they arrested the Michael Jackson Hologram, who was snooping around the Jeffersons estate. The cops have a hard time believing that the hologram was a black guy.
Back at the neighborhood, Stan is trying to find his dad, who was supposed to take him to the board games store, when Kyle tells Stan that the network has picked up his hashtag, and that he's trending. They watch the commercial for the Washington Redskins Go Fuck Yourself Holiday Special, and everything seems fine until they see that the special features CartmanBrah's live commentary. Kyle is angry how Cartman was involved with the special.
The television special, The Washington Redskins' Go Fuck Yourself Holiday Special, will feature various celebrities, holograms of deceased celebrities and LP commentary by Cartman. The special and its title are revealed to be the brainchild of Randy's ex-producer and Cartman, whom the producer employs for his youthful perspective, as a way to connect with the younger generation. The producer's staff, however, feel he has given too much power to Cartman, whose growing popularity results in his commentary window appearing not only on computers and other devices, but in thin air, in living rooms, corridors, etc. throughout the episode. Upon seeing a TV commercial for the special, Kyle is angered that his idea has been turned into a social media project, while his best friend Stan Marsh, is upset because he thinks his father, Randy is performing again as Lorde.
Randy and the Jackson hologram learn about the television special, and its intent, and agree to work together to stop it. When the Tupac Shakur hologram sent by Syntech Hologram Company to capture the Jackson hologram appears at the police station, the Marshes and the Jackson hologram flee to the Marsh home. Randy then learns that Stan and Kyle have been taken hostage by his ex-producer, and is confronted by the Shakur hologram, who appears in his home.
When Kyle asks the producer why he is doing this, the producer explains that when he became a grandfather five years ago, he intended to show his grandson everything about the entertainment industry. Then one day, when he asked his grandson who his favorite celebrity was, his grandson said it was online video game commentator PewDiePie. Bewildered that his grandson worshiped an insignificant internet personality from Sweden, and was unimpressed with any of the artists to whom he tried to introduce him, the producer says that with the television special, he will assimilate the younger generation's culture into his own, and foster an appreciation for real entertainment. Stan is astonished that the producer is "such a grandpa."
The Shakur hologram and the Jackson hologram decide to team up against the producer. When Cartman's window appears before the producer, he tries to have him shut down, but Cartman is trending so much, and has grown so powerful that he has reached "trend-scendence", "like Johnny Depp, but cool". As Cartman continues to appear on screens all around the world, he states that he is now "trends-gender" and therefore must be given his own bathroom, which was his motivation for being involved in this plan. The Shakur and Jackson holograms appear at the restaurant where the producer is hiding with the hostages. As Jackson fatally shoots the producer, Kyle, realizing that everyone on the planet can see everyone else on their computers, speaks out to his brother, Ike, admitting and apologizing for being a "grandpa". He accepts that Ike will develop his own generational interests, and admits that he was merely sore that Ike was a fan of Cartman in particular. He says that he just wants to be a family again. Ike and his friends resolve to get the public to "believe" again, and create a new trend with the hashtag #webelieveinyou, which Kyle, breaking the fourth wall, urges the home audience to spread. In response, PewDiePie's window appears, and his commentary is so powerful that Cartman's window is eliminated.
In the epilogue, Kyle says he finally managed to get their family to use the living room for an hour each night, though Stan is still confused over all those events that have just concluded and there seems to be no lesson. Kyle suggests that perhaps they are not going to understand it, it is the lesson, and that they have just witnessed the beginning of a new art form. He further says that at least YouTube celebrities are authentic, and have not been marketed to the public by corporations. They need to realize that this is the new generationofentertainment. PewDiePie's window then appears, and he thanks South Park for being on the show.
The episode received a B rating from The A. V. Club's Dan Caffrey, though he stated that "It was rushed, it was messy, and it may have been just a bit too much story for South Park, even for a two-parter."
Max Nicholson of IGN gave it a 6.8 out of 10, who stated "the climax of the entire episode (and arguably the season)...didn't tie everything together in the way that it could (and should) have."
Chris Longo from Den of Geek gave the episode 4 out of 5 stars, stating the episode "was incoherent, hilarious madness—its own artform." Longo's article also noted that, in real life, the topic #IHateCartmanBrah became the top trending topic worldwide on Twitter.