Oh, Taylor Swift and Nelly? "Old friends," she says on the Instagram.

The 1989 singer-songriter has made headlines on a weekly basis for her seemingly endless assortment of surprise guests on her massively successful 1989 Tour to the point of parody — from Fifth Harmony to Joan Baez — and she kept the tradition going during last night's concert in St. Louis, MO...with a little help from her HAIM BFFs, too.

During the concert last night, Tay brought out Nelly to perform — what else? — "Hot In Herre," which was hardly his first time in the Swift Squad. "@derrtymo has come out to surprise the crowd on my last 3 tours. I absolutely adore him.," she later wrote on Instagram that night.

And that's not all: There was choreography, too. "Yes we made up a dance yesterday in the dressing room," Taylor confessed in one of the video snippets she posted of the performance. Look at all that shimmying and sassy arm-flinging! They are. Get-ting. So hot.

So fun. And seriously, who hasn't gone up on stage with Tay by now? Watch clips of his cameo below.

See All of the Special Guests on the 1989 Tour:

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