On Saturday (June 18), birthday boy Blake Shelton turned 40 and celebrated the rock star way with a live performance at Country Jam in Grand Junction, Colorado. Right by his side was his musical sweetie, pop star Gwen Stefani, who joined the country crooner onstage for a lovey-dovey duet.

The collaboration occurred towards the end of Shelton's two-hour set, when Stefani joined the If I'm Honest singer for a live performance of their romantic opus "Go Ahead and Break My Heart," which they first debuted on The Voice (on which he serves as a coach) back on May 9. The unexpected duet was, much to the crowd's excitement, a complete and welcome surprise.

Later, Stefani took the stage once more after her beau made a very loud birthday wish to the audience.

"For my birthday, I wish I could hear and artist who could rock," he exclaimed. "That's my birthday wish!"

"You want some of this?" Stefani shouted back, joining him again. The No Doubt singer then played her rowdy electro-rock single "Hella Good," off her band's 2001 album Rock Steady. After bringing down the house, as well as demanding the crowd jump with her, the pop star gave Shelton one last birthday gift: a quick kiss in front of thousands of screaming fans.

Thanks to our friends at Taste of Country for the video, below!

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