Kristin Cavallari and Jay Cutler wore fun 80s outfits in celebration of Cutler's 30th birthday. Credit: Courtesy of Kristin Cavallari

Gnarly! Kristin Cavallari and fiance Jay Cutler played dress-up for his 30th birthday celebration, but the pair ditched fancy outfits in favor of an 80s-themed birthday bash over the weekend. 

"The hair is real, the cigarette is fake," the former Hills star tweeted about an adorable snap of the couple decked out in colorful, printed 80s wear. In the shot, Cutler wears a blonde mullet wig on his head to complete his totally awesome outfit: A loud, printed orange short-sleeve shirt, loose patterned pants and hot pink-and-white trainers. The Chicago Bears quarterback also had a cigarette dangling from his lips.

Cavallari, 26, donned a hot pink crop top, leopard-print tights and black leg warmers for her 80s-inspired look -- with a gold fanny pack to boot, of course. "Good times," she captioned another shot, in which she and two similarly festive pals posed for the camera.

The couple's fun night was a much-deserved night off from mom and dad duties. The pair are parents to son Camden, 8 months.

"Having Jay is really helpful," Cavallari told Disfunkshion magazine in a recent interview. "It's important to talk about parenting philosophies before having a child. You want to go in knowing how to raise them to avoid the arguments that can ensue. Being good parents is our top priority."