During a chat with VH1, the 16-year-old singer divulged the real inspiration behind her breakout single.
"I had this image from the National Geographic of this dude just signing baseballs," she explained. "He was a baseball player and his shirt said, ‘Royals.'"
It turns out that the New Zealand native was so struck with the image that she immediately wrote the song based on what was written on the player's jersey.
She added, "I really love that word…I'll pick a word and I'll pen an idea to that. It was just that word that I was like, ‘This is really cool.'"
The picture in question was that of former Kansas City Royals star George Brett who was snapped greeting fans and autographing balls outside of a stadium.
But of course, it wasn't just the word that prompted the teenager to write one of this year's biggest tracks.
She also confessed that she's "had this obsession with aristocracy" since she was a wee one.
"The kings and queens of 500 years ago, they were like rock stars. If there was a TMZ 500 years ago, it would have been about Henry VIII and Marie Antoinette and all those people, because their lives were just fantastic."
Inspiration aside, the song is undoubtedly a massive success.