The Jonas Brothers brought their 2019-2020 Happiness Begins Tour to Nashville on Tuesday night, (Sept. 10), and their Bridgestone Arena show got a little bit "happier" thanks to a surprise appearance from Dan + Shay. Press play above to watch the two superstar acts team up for a rendition of the country duo's "Tequila."

Though the Jonas Brothers may be a pop act, that didn't seem to stop their audience from welcoming the special guests to the stage with rousing enthusiasm. In fact, there seemed to be quite a few avid Dan + Shay fans in the crowd, who sung along to every word of the song at the top of their lungs.

The two groups have been friends for a few years. According to E!, the country duo met Nick Jonas and began getting to know each other after performing together at the 2015 ACM Awards.

"Our managers connected us first," Jonas explained at the time. "And I heard that they liked what I was doing and I love what they were doing, and it just happened pretty organically."

In fact, the Brothers are such big fans of Dan + Shay that Joe Jonas enlisted the duo to perform at his wedding to actor Sophie Turner. Hours after performing at the 2019 Billboard Music Awards, the two singers headed to a Las Vegas, Nev. chapel to give a rendition of their hit love ballad "Speechless" for the special occasion.

After the wedding, Dan + Shay admitted to The Boot and other outlets that their participation in it had come as a surprise to everyone -- even, to a certain extent, to them. "They texted us three or four days in advance. I feel like when we got the text, we thought it was a joke or a prank," the  duo's Dan Smyers recalls. "True enough, after the [2019 Billboard Music Awards on May 1], they were like, 'Hey, meet us here.' There was an Elvis impersonator doing the wedding. It was a whole thing. It was great."

Tuesday night's Happiness Begins Tour stop featured a stacked evening of surprises, even beyond Dan + Shay's appearance. Earlier in the evening, opening act Bebe Rexha invited Kelsea Ballerini to the stage for a rendition of massive crossover hit "Meant to Be," which Rexha originally recorded with Florida Georgia Line.

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