Taylor Swift popped by 'Jimmy Fallon' on Wednesday, Aug. 13 to make a few announcements and rock what she dubbed a "tri-tail" as Nerdy Natalie.

Swifties, if you're expecting something major during the 'Red' star's live stream on Monday, Aug. 18, you're in luck! "There could be one announcement, or there could be multiple announcements," she teased when Jimmy grilled her for exclusive details on the event. Taylor kept mum otherwise, but she also didn't deny it when the late night host confirmed a "big secret announcement"!

The 24-year-old singer also confirmed that she'll be performing at this year's MTV Video Music Awards on Aug. 24. She was in a secret-keeping mood, because once again, she wouldn't budge when Jimmy begged for more info! "We're planning it... and we're planning it," she said mysteriously.

Taylor wasn't up for revealing what she's got planned in the next month, but she was up for rocking braces, oversized glasses and a tri-pony -- a one-up on pigtails -- for her role as Nerdy Natalie in Jimmy's 'Ew!' skit.

"My name's Natalie and I'm 13 and I like to eat apricots and I have a bandaid collection," she said in an introduction to Jimmy's mean teen character Sara. Natalie also told Sara that her mom hasn't let her watch TV "since Miley Cyrus twerked" and that she likes to sit in an attic alone and create popsicle-stick castles.

The best part? That last part is a true story -- from Taylor's own childhood!

"I have this scar on my leg, it's a very prominent scar that I've probably had since I was 10 or 11," she told 'The Tonight Show' host. "When I was 10 I used to sit up in my attic and make castles out of popsicle sticks using an industrial-strength glue gun."

She continued, "One day I was really aggressively creating a slide, because I had these little toy bears that lived in [the castle], and they needed a slide. ... I was creating a slide, gluing, gluing, gluing, and then suddenly I was gluing off the table and a glob of hot glue was just there." She pointed to her thigh, explaining that she then tried to pull the glob off -- and "17 layers of skin" came with it. Ouch!

At least her scar ended up as hilarious skit material over a decade later, right?

Swifties, don't forget (as if you could) to tune into Taylor's live stream on Yahoo on Monday, Aug. 18 at 5PM ET, and check out her performance at the MTV VMAs on Sunday, Aug. 24 at 9PM ET!

 See Taylor Swift + More Stars' Yearbook Photos

More From 99.9 KTDY