Earth, Wind and... Wait for It - S3-E12
Trivia: The fire inspector tells the investigators to fill out form IG-88. IG-88 was a robot bounty hunter from 'The Empire Strikes Back.'.
Trivia: Alan Ruck, who plays the bank robber, is (arguably) best known for his role in Ferris Bueller's Day Off, where his character's name is Cameron. In this episode, Ruck plays a bank robber who takes hostages, including Gus. The SWAT commander that attends the bank robbery (a character who hasn't existed before) is named Cameron. Possibly a deliberate choice given Psych's frequent pop culture references. ADDITIONAL: Series 8, Episode 3 - Ruck co-stars as a news weatherman; when Shawn introduces himself, he says .".and this is Gus, my black Cameron" - a much more clear reference to the Ferris Bueller character.
Chosen answer: "Psych: The Musical" was supposed to air during the regular season 7 schedule, before Chief Vick is suspended and Jules discovers Shawn's lie, but the network decided to push it back to air as a special episode, sort of as a tie in with the holiday season and a lead in to season 8, which was to begin only a couple of months later.