Rehab by Amy Winehouse
Rehab, but they added something in the beginning.
Demi sings the theme song and she sings in some of her sketches on so random, she sang a hip hop song on the first episode of sonny with a chance. She also sings in the season 2 episode "sonny with a song" and she sings in another season 2 episode called "high school miserable" and she sings a tiny bit in the s2 episode "legend of candy face".
Season 4|Episode 19
bones sings in "The Wannabe in the Weeds" season 3 episode 14.
season 1 episode 1
Phoebe sings inappropriate songs to school children in Season 2, Episode 12, The One with the Superbowl, Part One. She is approached by a man to asks her to sing at the library. The parents complain about the lyrics so Phoebe changes them to make the content more appropriate. She sings at Central Perk and all of the school children attend because she is the lady who sings the truth.
She sings this song in season 1- episode 13 Hell-O to Jesse when he breaks up with her.
"Whale Whores" (Season 13 Episode 11)
She sings eternal flame for Matt on season 2 episode 16 - The House Guest
The whole glee club sings Push It in season 1 episode 2, Showmance.
I can't think of one where she turns lesbian, but in the episode 'Brian Sings and Swings' (UK Season 5/US Season 4), she joins a lesbian club at school because she wants to fit in and changes her image to the stereotypical lesbian. Hope this helps! :/
The episode Canada on Strike (episode 4, season 12).