You and Katsuki went out for food, you decided to pay, so you pulled out your wallet, and opened it just enough for him to see a picture of him and you in there, once you paid you closed your wallet and you two went back to your car, and sat in there to eat, he decided he would bring it up once you were done eating

You finished eating now and just sat there for a bit "So, who's picture is that in your wallet, dumbass?" He looked at you, as he smirked