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(Yahoo!) - This week, Nashville served as host to the megawatt benefit concert "We're All for the Hall," a special show for the Country Music Hall of Fame spearheaded by Keith Urban and Vince Gill. Carrie Underwood was just one of the stars on the bill, performing Dolly Parton's "I Will Always Love You," as well as her own 2007 hit "Last Name."

Regarding the latter tune: Do you know what actually inspired it? Although it's hard to believe, a short-lived fling was the catalyst for the Grammy-winning single.

Take it from Underwood herself. The superstar told the "All for the Hall" crowd the story behind the song before performing it.

"Before I met my beautiful, wonderful, perfect hockey husband [Nashville Predator Mike Fisher], I had met this guy. I got together with [songwriters] Hillary Lindsey and Luke Laird to write, and we were goofing around like we always do. I was telling them about this guy I met. They asked who he was, and I said, 'Y'all! I don't even know his last name!'"

She continued: "We hadn't even dated or anything and it didn't turn out the way this song did, but I said, 'We need to turn this mess into a song!' And this is it."

The lyrics of the song are a bit over-the-top to be autobiographical, detailing a one-night stand (It started off, "Hey cutie, where are you from?"/And then it turned into, "Oh no, what have I done?"/And I don't even know his last name) that culminates in a quickie Vegas marriage (I don't even know my last name).

However, exaggerated or not, the song stands out in Underwood's catalog. Unlike fellow country megastars such as Taylor Swift, Underwood has previously said she never writes music about her past relationships.

In 2009, when she was asked by Esquire if the song "Cowboy Casanova" was about ex-boyfriend Tony Romo (as rumors had it), she flat-out denied the speculation. "I would never immortalize a guy that did me wrong," she said. "I would never give him that much credit."

Perhaps this means the little fling that inspired "Last Name" ended on a good note? At any rate, Underwood and the event's other participants — Reba McEntire, Darius Rucker, and Kacey Musgraves, just to name a few — ended the evening on a good note, helping to raise around $600,000 for the Country Music Hall of Fame.

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