Taylor Swift performs onstage at Sprint Center on Sept. 21, 2015 in Kansas City, Missouri.
Taylor Swift played the second of two shows at St. Louis's Scottrade Center last night (Sept. 29) and, well, things got a little heated -- in a good way.
Taylor Swift Denies Mansion & Marriage Rumors
To celebrate Haim's last night on the tour, Swift invited them to join her onstage as back-up dancers for Nelly, who, naturally, performed his 2002 hit "Hot In Herre" for the hometown crowd.
The Weeknd Holds Atop Hot 100, Taylor Swift Hits Top 10 With 'Wildest Dreams'
Watch Taylor's snippets of their performance below, which include very careful choreography and emphatic singing to the song's unforgettable chorus. According to Taylor, it was "the highlight of [their] friendship thus far" (pretty understandable).
BUSTING LOOSE bc Tay, Nelly & HAIM threw it back 2night w/ 'Hot in Herre' #1989TourStLouis pic.twitter.com/LJiJvaNegm
— Taylor Nation (@taylornation13) September 30, 2015
The highlight of our friendship thus far @HAIMtheband PS WE LOVE YOU @Nelly_Mo #1989TourStLouis pic.twitter.com/3USBBookRg
— Taylor Swift (@taylorswift13) September 30, 2015
"WHAT?!" @Nelly_Mo @HAIMtheband #1989TourStLouis pic.twitter.com/lZYDlJNmsS
— Taylor Swift (@taylorswift13) September 30, 2015
This isn't even the first time Taylor has invited the rapper on stage -- check out their 2013 duet of "Hey Porsche" below, as well as their 2011 (!) performance of "Just A Dream."
Watch Taylor Swift and Mick Jagger Perform Rolling Stones' '(I Can't Get No) Satisfaction'