It's no secret that Taylor Swift and Lena Dunham are BFFs these days.

During an interview on "The David Letterman Show" on Tuesday, the "Welcome to New York" singer revealed that how she and best friend Dunham first bonded. It seems Swift and the "Girls" creator were basically each other's secret admirers.

"I was watching Girls when it first came out about two years ago and I just thought, 'She's so empowering. This person writes, directs and stars in this incredible show.' So I did what you do when you're interested in someone: I Googled her and went to her Twitter and the first thing I saw was her quoting my lyrics. At first I thought, 'She has to be doing that ironically. She's clearly making fun of me.' I have this big loser complex from school. But it turned out she was following me and it was completely unironic and she actually liked my music," Swift told host Letterman. "She direct messaged me and she said, 'We need to be best friends. I feel like you've been my best friend in my head for months and almost year now, so I need to see you in person and I will lavish you with compliments in person.' And she did do that. And we've been best friends ever since."

Swift, 24, and Dunham, 28, who both reside in New York, are each known for their empowering feminist views and have become undeniable pop culture icons in recent years.

According to Swift, whose fifth studio album "1989" was released on Oct. 27, says that she and Dunham connect over their professions as well as their personalities.

"I think since we're both writers...we have a lot to relate to each other on, and we're also both way enthusiastic about everything," she said.

Swift, who was recently named the new face of New York tourism, also dished on her passion for the city she has called home for the past year.

"When I love something, I'm very, very vocal about it," she told Letterman. "Any time I talk to anyone or any time I do an interview, I'm like, 'You don't understand. You have to go there now. You have to go to New York. Just drop what you're doing, and go there. It's amazing. It's the greatest place ever.' And I guess the city picked up on that. They're like, 'She's the most enthusiastic, obnoxious person to ever love New York. She loves it with like 18 exclamation points afterward, underlined.'"

"I'd been obsessing over moving to New York for a year but I didn't find the perfect place until winter last year," added the "Shake It Off" crooner. "So, I've been there ever since and I had the most amazing summer here. All my friends are here!"