Castiel was used to having to be in disguise by now and when Dean told him they had to be the FBI once again he didn’t question it. Once he was changed into his suit him, Dean, and Sam, hopped into the impala and drove off. During the drive Sam informed him about what has been happening that they have to look in to.
He didn’t expect to walk into a building where there were people up on a stage dancing while people gave them money. He was surprised at the outfits he saw especially since most the people were barely clothed- it wasn’t what he expected since he’s only been to a few bars with Sam and Dean.
For some reason he couldn’t take his eyes off one of the main dancers… you. you weren’t center stage but you were still clearly with a pretty big audience to the side and the way you were dancing had him mesmerized.