"Mash Off" is the sixth episode of the third season of the American musical television series Glee, and the fiftieth overall. The episode was written by Michael Hitchcock and directed by Eric Stoltz, and originally aired on Fox in the United States on November 15, 2011. Special guest star Idina Menzel is featured as rival glee club director Shelby Corcoran, and she and Will Schuester hold a mash-up competition between the Troubletones and the New Directions. Santana mercilessly taunts rival glee club member Finn, who ultimately responds by publicly accusing her of cowardice in her relationship with Brittany, thereby revealing to their fellow students that she is a lesbian. Sue Sylvester starts a propaganda campaign against Burt Hummel, her chief rival in the special election for congress.

Burt Hummel is a fictional character from the Fox musical comedy-drama series Glee. The character is portrayed by actor Mike O'Malley, and first appeared on Glee in the fourth episode of the first season, "Preggers". Burt was developed by Glee creators Ryan Murphy, Brad Falchuk and Ian Brennan. He is the father of gay glee club member Kurt Hummel, and works as a mechanic in Lima, Ohio, where the series is set. He eventually begins a relationship with Carole Hudson, the mother of another glee club member, Finn Hudson, and the two marry in the second season episode "Furt". In the third season, Burt runs in a special congressional election and wins. O'Malley was a recurring cast member during the first season, and was upgraded to a series regular for the second season of the show, but returned to the recurring cast for the third season onward.