Billie Eilish
photo: Splash News

Anyone who watched Billie Eilish's mind-bending SNL performance of "Bad Guy" was most likely blinking at the screen in disbelief. 

I know I was sitting there trying to think of how exactly the trippy stunt was pulled off. Viewers are no longer left wondering, because the artist showed the work that went into the set in a behind-the-scenes video from SNL

With two sprained ankles, the 17-year-old scaled the walls of her stage. Oh, and she was dancing and jamming along to her creepy-cool hit. The artsy performance was in line with the teen's aesthetic, and was apparently one of her most rehearsed shows to date. 

First, have your mind blown by the performance without any explanation. 

Eilish always pushes limits with her visuals. She's let a tarantula crawl in her mouth, had black liquid flow into her eyes, and has even given herself nightmares because of the dark vibes in "Bury a Friend." So it came as no surprise that her first SNL appearance would be as over-the-top as the rest of her collection of videos and performances. 

Now, see how the magic was made. 

Film buffs may have been able to tell you exactly how the artist scaled the walls of her SNL stage, but us common folk were staring dumbfounded. It's actually not a totally new idea, and Fred Astaire was one of the first to try out the technique in the 1951 film Royal Wedding. It was also featured in the hotel dream sequence in Christopher Nolan's Inception

Eilish was thrilled to perform with her brother and music partner. 

Eilish has already reached levels of success that people who have been in the industry for years haven't experienced. Eilish and her brother Finneas O'Connell create music at home in their own recording studio, and have been well-received by fans and critics alike. The siblings were beaming at the SNL studio, she wrote to her Instagram: "MY BROTHER IS MY BEST FRIEND AND WE DID SNL LAST NIGHT AND IT WAS A PEAK LIFE EXPERIENCE. WOW. THANK YOU LIFE FOR GIVING ME WHAT I HAVE." 

The show's Instagram shared some topsy-turvy photos of the singer. 

Both of her performances on Saturday's show were prime examples of Eilish's personality. The first was a trippy and weird over-the-top display, while the second was a raw, emotional, and stripped-down song. Fans seemed to love both equally. 

Her second set was just as gripping, but more low-key and emotional. 

Naturally, one of her most emotional songs to date would be a raw and stripped-down performance. The siblings shared the stage and sounded lovely together. In their matching costumes, they looked like a perfect musical pair that clearly work extremely well together.