Carrie Underwood and Rascal Flatts singer Gary LeVox are fans of NKOTBSB (that's boy bands New Kids on the Block and the Backstreet Boys together, for those of you who might not know). They're proud, go-to-the-concert, throw-your-hands-in-the-air-and-wave-'em-like-you-just-don't-care NKOTBSB fans, at least in Underwood's case, as you'll see from the fan-captured video below of Underwood rocking out.

Both country stars caught the NKOTBSB show at the Bridgestone Arena in Nashville this week, and Underwood (and her husband, Mike Fisher) and LeVox get their photos taken with Howie Dorough from the Backstreet Boys. Underwood was even filmed having the time of her life during the concert, waving her arm back and forth during New Kids on the Block's 'Hangin' Tough.' Who knew that Underwood was such a NKOTB fan? She must have been around 7-years-old when the group was at the height of its fame, so perhaps little Carrie was all about Jordan Knight and Co.

Even Underwood's husband, Fisher, whose arm was in a sling, enjoyed a little boy band fun, as seen in the backstage picture. We'll assume that Underwood dragged her man to the show, and that makes him a very good guy.

Watch a Video of Carrie Underwood Rocking Out to New Kids on the Block