On first listen, Billy Ray Cyrus' biggest contribution to the cultural phenomenon that is "Old Town Road" is obviously his classic, gravely refrain (followed closely by a reference to "Fendi sports bras"). But listen more closely and you'll hear perhaps Cyrus' most important contribution.

"I always loved to whistle," Billy Ray Cyrus tells Taste of Country, "But really nobody let me whistle on a song until when I whistled on 'Old Town Road.' I got a note back from Lil Nas and [beat producer] Kio that said, 'That's fire.'"

That's right — near the very end of the song, you can hear Cyrus whistling a little ditty over the closing chords. And it's probably the most understated part of the performance, but clearly one Cyrus is proud of.

The rest of the team must have enjoyed it too, because the whistling made its way onto all subsequent remixes, including taking a prominent role on Diplo's remix.

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Technically it means Billy Ray Cyrus even collaborated with Korean "K Pop" powerhouse BTS. "I think I'm known as 'The Whistler' to BTS," Cyrus reveals, laughing. "When BTS joined the record, all they left in there from my bit was the whistle."

Cyrus has since used whistling even more in his songwriting. "It's interesting, I wrote a song yesterday where only the melody was coming to me," the "Achy Breaky" star shares. "So I said to myself out loud, 'Just whistle the words' — which is silly, you can't whistle words — but I hit record and just whistled the melody part."

Lil Nas X's "Old Town Road" set a Billboard chart record by staying at No. 1 on the Hot 100 chart for at least 17 straight weeks — more than any other single in the history of the chart. The song was already taking off when Cyrus joined in on a remix (now the most popular version of the song), thanks in no small part to controversy when Billboard kicked the song off its country charts.

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