Carrie Underwood sent happy birthday wishes out to her best friend in a funkadelic Instagram post on Friday (July 21).

Underwood's best friend is Ivey Childers, and she often shares pictures of some of the fun they have together with their husbands. Childers' husband Mark Childers is Underwood's bass player and band leader, and he and Ivey often hang out with Underwood and husband Mike Fisher.

In the picture above, Childers is decked out in an outlandish '70s retro getup complete with jeans, flower print shirt and an afro wig (hopefully!) that would make the members of Grand Funk Railroad green with envy.

"HAPPY BIRTHDAY to this groovy gal! I am so thankful for you in my life!" Underwood writes to accompany the image. "Cheers to oh so many more birthdays...hopefully spent together!"

Carrie Underwood and Her Husband's Cutest Pics Together

The photo looks to have been taken during a wedding shower for the daughter of Underwood’s stylist, Melissa Schleicher, who is getting married in September. Underwood shared more pictures from that groove-tastic evening on July 16, including a video of the psychedelic foursome jamming along in the car to Chic's "Good Times."

Ivey owns a gourmet bakery called IveyCake, and she got the call to bake a custom cake for the celebration when Underwood won American Idol, but the two didn’t actually meet until she began dating Childers several years later, according to CMT. They have since become inseparable, and Childers designed the cupcake tower that was featured at Underwood’s wedding to Fisher in 2010. Childers looked to Underwood when she had her first child in 2016.

"We’ve been friends for gosh, seven or eight years now," Childers tells CMT of Underwood. "We got married a year apart, we’re having babies a year apart. We’ve kind of experienced all the milestones in life together. She’s most definitely my very best friend."

Underwood has no concert dates on the books for the rest of 2017, and she's been taking it easy this summer, recently posting a bikini shot of herself relaxing by the lake and stressing the importance of getting back to nature.

Last Year Carrie + Mike Took a Vacation, and They Shared Pics! 

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