10/03/2013 10:03 am ET Updated Oct 03, 2013

Taylor Swift First Heard Tegan And Sara's 'Closer' In The 'G.B.F.' Trailer

Back in August, Taylor Swift brought "her friends" Tegan and Sara out on the Staples Center stage in Los Angeles to sing their hit single, "Closer."

"I remember hearing through the grapevine that she was a fan. I was like, there's no way!" Tegan told Rolling Stone after the concert. "Then her manager called a couple of months ago and said Taylor is obsessed with the record and she'd love to have the girls up. I made a joke that we'd change the date of the birth of our child to make it happen."

So, how did Swift stumble upon the Canadian indie rock sister act in the first place? By watching the trailer for "G.B.F."

"There are elements to 'G.B.F.' that only a big studio film should have been able to merit," director Darren Stein told Tribeca Film in a new interview. "But my music supervisor knew Tegan and Sara, and they loved the movie. Then Taylor Swift discovered their song in the trailer for 'G.B.F.,' and that's why she invited them on stage to sing at her concert."

Directed by Stein ("Jawbreaker") and written by George Northy, "G.B.F." is about a gay high school student who gets inadvertently outed by his classmates and then becomes best friend to the school's three biggest mean girls. The indie made a splash at the Tribeca Film Festival in April of this year, winning fans with its pop culture acuity and a Spotify-ready soundtrack that included Tegan and Sara.

"G.B.F." debuts on DirecTV in November before a on-demand and limited theatrical rollout in January of next year. Watch the trailer below, and imagine Taylor Swift sitting at her computer and doing the same thing. Stein's full interview, well worth a read, can be found at Tribeca Film.