"I'm not cocky," Christina Aguilera explains in her new disco banger, "Vanity." "I just loooove myself, bitch!" Thanks for clearing that up, Xtina. Humility has never been this lady's problem — on her last album, the 2006 double disc Back to Basics, she was in way over her head aspiring to be a jazz singer, comparing herself to Billie Holiday and John Coltrane. But she's a lot more fun now that she's getting her Lady Gaga on instead. She goes for an electro makeover on Bionic, dressing in Gaga-style robot glam and cranking up the Auto-Tune.

Bionic has her friskiest synth beats since the days of "Genie in a Bottle," with surprisingly punk-minded collaborators like Le Tigre, Ladytron and M.I.A. "My Girls" is a hilarious disco anthem where Aguilera gives it up to her new riot-grrrl pals: "My girls wear lipstick while they're making my beats/They got guitar picks in their purses, Louboutin on their feet." Things stall mid-album with a string of dull ballads — "Sex for Breakfast" is cold cereal, and "Lift Me Up" is the inevitable Linda Perry snoozer. "I Am" is an intriguingly Björk-ish collabo with Australian folkie Sia. But "Vanity" says it all, especially when the backup chorus chants the wedding march as Christina vows, "I take myself to be my lawful-wedded bitch." Cheers to the happy couple.

“Youth Knows No Pain”

“Like on 'Youth Knows No Pain' — we are the ones that should demonstrate, because we can take it,” Likke Li said. “We can pierce ourselves, take Ecstasy, dance all night and still go to work at our McDonald's jobs.” Despite the hedonistic sentiment in the song, the Swedish singer also admitted in hindsight her youth had repercussions. “I remember when I was 18-19 and feeling that I know it all,” Li said. “I always feel that I know it all. But that song is about realizing you don’t, and reflecting, ‘Boy, if I only knew what would follow.’”