Imagine: You walk into a karaoke bar in Nashville and see Lionel Richie singing his cottony R&B hits with a bunch of country stars. Best vacation ever! OK, Rascal Flatts make “Dancing on the Ceiling” feel strained, and Jimmy Buffett doesn’t sound like he really wants to "fiesta forever." But these collaborations jell because Richie's style is so expansive, musically and emotionally; the steel guitar on "You Are" enlarges the song's unabashed gratitude. And when Little Big Town ease sparkling harmonies into "Deep River Woman," everybody in the bar, even Blake Shelton, knows better than to try to top it.

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• Photos: Random Notes

“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.’”