At McKinley, Puck admires Shelby from afar and decides he is in love. He and the New Directions boys perform Van Halen's "Hot For Teacher." Meanwhile, Sue begins a TV smear campaign that suggests Burt Hummel has a baboon's heart. Kurt confronts Sue and likens her dirty tactics to the same tactics Britney is using to try and get herself elected as class president. In the staff room, Will and Shelby decide that they should channel their kids' fighting spirit into a "mash off" competition between their New Directions and Trouble Tones glee clubs. They set the tone by performing for their students a mash up of "You and I" by Lady Gaga and "You and I" by Eddie Rabbitt and Crystal Gayle.
After class, Puck approaches Shelby and admits that he is in love with her. Though Shelby says that their kiss was a mistake, Puck persistently argues that a relationship between them would be perfect. Back at glee practice, the kids in New Directions argue about which songs they should perform for their mash up. Finn suggests that Rory takes the lead on a Hall and Oates number. Later, the boys get into a trash talking session with Santana and challenge the Trouble Tones to a game of dodge ball. Meanwhile, Quinn attempts to get closer to her daughter by asking Shelby if she could join the Trouble Tones. Rachel also seeks out Shelby as she asks her mom for help in applying to the New York Academy of Dramatic Arts.
The rival glee clubs assemble in the gymnasium and compete in a physical game of dodge ball. While playing, the kids sing a mash up of Pat Benatar's "Hit Me With Your Best Shot" and "One Way Or Another" by Blondie. When the Trouble Tones gang up on Rory and give him a bloody nose, Kurt comes to his aid and says that the clubs need to stop treating each other so poorly. After the game, the Trouble Tones decide that Mercedes will lead them in an Adele mash up, and that they should start to be nicer to their rival glee club. Santana, however, finds Finn and once again makes fun of him. In retaliation, Finn tells Santana that he thinks she's an insecure coward who can't admit that she's gay and in love with Brittany.
Sue continues to use her television show to smear Burt's personal life. Burt angrily watches and tells Will that they need to start fighting fire with fire. Meanwhile, Puck visits Shelby and admits that Quinn has been trying to get Child Services to take Beth away from her. Back at McKinley, the mash off begins as New Directions performs a Hall and Oates mash up of "You Make My Dreams" and "I Can't Go For That (No Can Do)." Later, at the McKinley debate for class president, Brittany promises the student body that she will go topless every Tuesday if she's elected. Kurt then gives an inspirational speech about what it's like to be bullied and how he pledges to do anything he can to stop violence, including banning dodge ball. Rachel then takes the microphone and admits that Kurt is the best candidate for the job, and reveals that she will be voting Kurt for class president.
Quinn visits Shelby with gifts for Beth, but Shelby kicks Quinn out after letting her know that she's aware of the plan to regain custody of Beth. Meanwhile, Santana is called into Sue's office by Sue, Will and Burt. A tape is shown to her of a congressional candidate's smear campaign against Sue, which includes suggestions that Sue favors Santana, who is actually a closet lesbian. Santana is devastated and says that she hasn't even told her parents yet. The scene segues into the Trouble Tones' Adele mash up of "Rumor Has It" and "Someone Like You." Finn whispers to Rachel about how great Santana is, but Santana misreads it and blasts into Finn for ruining her reputation. When Finn maintains that he has no idea what Santana is talking about, she slaps him across the face.
Wow, wow and wow. As soon as I'm done typing up this recap, I am going back and watching every minute of "Mash Off" all over again. Pardon my enthusiasm, but this was the best episode of "Glee" since the show's first season. Why? The songs were diverse, the performances were flawless, and a key storyline (Santana's homosexuality) was advanced. What more can you ask for in a 60-minute episode? Thank you, "Glee," for bringing us back tonight to what has made this show so special.