3x15 - Maniac Mansion

Tina forms a band and enters a contest. While rehearsing, she finds out that Lorrie isn't dancing right because she's shy. Tina thinks about firing her, but feels bad because Lorrie is her friend. Then Lorrie comes over to tell Tina she wants to quit. Tina makes her sing loud enough so she can hear it, and finds out that Lorrie is the best vocalist in the group. To give Lorrie the attention she deserves, Tina fakes her voice going out during the show. This forces Lorrie to become the main singer, and she was a big hit. However, another contestant beats them out for first place in the end.