We all know they're friends, but do you remember when Kellie Pickler and Taylor Swift teamed up for a Top 10 hit?

Pickler came to national attention when she hit the stage of American Idol during its fifth season, placing sixth. She released her debut album, Small Town Girl, later that year, within a week of the then-unknown Swift releasing her self-titled debut.

Both albums were successful, and the young ladies hit the road for a tour with Brad Paisley that saw them become fast friends. They collaborated on a song called "Best Years of Your Life" on the road that was inspired by Pickler's own love life.

"I had went through a really bad breakup a while back, so we wrote the song about the relationship that went sour," Pickler recalls to the Boot.

Swift joined Pickler in the studio to provide background vocals for the track, and she also appeared in the video for "Best Days of Your Life." Released as the second single from Pickler's self-titled sophomore album, "Best Days of Your Life" reached No. 9 on Billboard's U.S. Hot Country Songs chart, giving the singer her biggest chart hit to date. It was certified Gold on July 2, 2009.

"It’s so funny, because Taylor always says that she has the “Picture [to Burn]” song, and Carrie Underwood has “Before He Cheats” … and now “Best Days of Your Life” — that’s my kiss-off song!" Pickler says. "[My ex] has heard it, and so has the person he’s with now, so I guess it’s bittersweet."

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