If there's one song on Garth Brooks' upcoming new album, Gunslinger, that will have even the most die-hard fans scratching their heads, it's "8teen." The country star says that the song -- track No. 9 on the disc -- is one of his most personal yet ... and will send his superfans on a musical treasure hunt.

"If there is such thing as a 'Garth Brooks Fan Club,' I think that's going to be their anthem," Brooks told Taste of Country in a recent interview. "Because every word is some kinda hidden-trick treasure that goes back to something else, so they get to dig in and find it."

Brooks compares "8teen" to "Mom," which was the song closest to his heart on his last record, 2014's Man Against Machine. The singer thinks that his fans are going to love "8teen" as much as he does, even as it challenges even his most dedicated listeners.

“No one in the world is going to know what it’s about,” Brooks teases, “but people that know us, know our history and have known us for 30 years, are gonna start digging in and finding it’s got a lot of hidden little jewels in it.”

Gunslinger hits stores as a standalone album on Nov. 25, but fans can get it two whole weeks early by purchasing The Ultimate Collection on Nov. 11; in addition to Gunslinger, the Target-exclusive box set includes nine discs of hits. Brooks will also release a Christmas duets album with wife Trisha Yearwood on Nov. 11.

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