Keith Urban gave fans more than just his hits at a surprise pop-up show at Buc-ee’s in Athens, Ala., on Friday night (Aug. 16). The country superstar donned a Buc-ee’s T-shirt and waited on customers ahead of his gig, serving up some of the chain’s beloved brisket. In the fan-captured video below, Urban sports the T-shirt and a cowboy hat as he learns to add the sauce and cut the meat for the chain’s signature sandwiches: Urban turned to social media on Friday afternoon to give fans just a few hours’ advance notice about the show, which took place in the parking lot on a stage set up for the o…