Billy Ray Cyrus didn't know what a Fendi sports bra was before 'Old Town Road'.

The 57-year-old singer offered to work on a remix of the track with rapper Lil Nas X after Billboard ruled it ineligible for the Hot Country Songs chart for not fitting the genre and songwriter Jozzy - who worked on the remix with Billy - has revealed that the star had no idea what some of the lyrics meant.

Jozzy told Variety: ''Well it was one of those things where I didn't want him to talk about anything country. It was like, 'Bro, no moonshine, no cigarettes, no red cup in hand... since Lil Nas X is stepping into your world, step into his world'. So Fendi sports bras, Maserati sports cars, 'hat down cross town living like a rockstar'.

''Billy was lit, I'm telling you. His wife, Tish, was such a supporter. She was, like, 'Bae, you gotta say that'. He didn't know what a Fendi sports bra was. Then I said, 'Your wife has one' She's, like, 'Yeah I got one!' I was, like, 'Bro, just say it'.

However, Jozzy has admitted that she only knew Billy from 'Hannah Montana' before working on the song together.

Jozzy said: '''Hannah Montana', of course. My momma used to think he was hot as **k. She loved him, that's all I really knew. ... That's why I was more open to do it, because it was, like, 'This is for my momma'.''

The song has gone on to huge success and Billy recently called it a ''movement''.

Explaining how he got involved, he told the New York Post: When I saw [the song got disqualified], I wrote to Lil Nas on Twitter, and I said, 'Waylon Jennings told me, What is the definition of an outlaw? One who has been outlawed. Welcome to the club'. But music fans were smart enough to see through that, and they said, 'We don't need nobody to tell us what we like'. Like Lil Nas says, 'Can't nobody tell me nothin'. This song became the power of the people. It feels more like a movement.''