Derek works at a porn store. One day, Stiles comes in asking all sorts of TMI questions about different toys. That's where it all starts.

“You know what I am?” Kuroo asks. He’s not looking up at Kenma, instead concentrating too much on pushing his shirt up over his chest. …Shit, Kenma owes Shouyou a thousand yen. (( or: shouyou and kenma make a lot of bets, kenma meets a ridiculously handsome stranger, and a ridiculously handsome stranger treats kenma to a night he couldn't forget even if he wanted to. it's a good thing he doesn't. ))