That. Just. Happened. Every Spice Girls fan's heart skipped a beat on Sept. 9 after Emma Bunton, aka Baby Spice, shared a video of Lady Gaga singing a Spice Girls song together.

Like we said, That. Just. Happened.

Baby Spice shared a video of the "Bad Romance" singer singing (a capella, no less) a segment of the group's 1996 classic "2 Become 1."

#2Become1 with @ladygaga..! 💋#shenanigans #duet

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"#2Become1 with @ladygaga..! 💋#shenanigans #duet," Emma captioned the video.

The Spice Girl screamed with delight at the end of the video, as did many of the group's fans surely did.

Entertainment Weekly said that Gaga and Emma hung out when Gaga visited UK's Heart FM radio show to promote her new single, "Perfect Illusions."

The Spice Girls could soon be as busy as Gaga, as well. Several of the members -- Emma, Mel B and Geri Halliwell -- have decided that they will do something to celebrate the 20th anniversary of their debut album. They've dubbed themselves GEM, an acronym for their first names, if you hadn't figured that out.

"We are going to do something... us three. We're going to perform and celebrate, you know, together for the people," Mel B told James Corden on Thursday. "I think because we're a British band we're probably going to start in London and then work our way around to see wherever else wants to see it."

When asked why it was only going to be a three-girl group, rather than the original five, Mel joked, "because the other two b------ didn't want to do it!"

Mel added, "My other two fellow lovely ladies -- you know Victoria [Beckham is] busy with her great fashion line, Mel C is doing her own album -- so they gracefully said 'you three go ahead and do it.'"

In July, the three women put out a video to tease their fans about a possible tour. Website

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"We've been thinking, we have the best fans in the whole entire world," Mel B says at the beginning, while Geri adds, "You've stood by us for 20 years, and we want to say a big thank you."

The three women go back and forth chatting with each other.

Emma says, "We've had our ups and downs, but you've always been there."

Insert Mel C. "And we want to celebrate and have a party," Brown continues, teasing the a tour may be in the works for the trio. "And when we do, you're all invited!"

The video ends with a message that reads "Happy 20th birthday to all our fans."

It continues, "This is a celebration for you! We hope to tell you soon, what you want, what you really really want. #WANNABE."

20 years ago my back garden - wannabe entered the charts , and our amazing journey began.

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Maybe Monster Spice can join them if they need another person?