You and your best friend are having a sleepover, playing card games and goofing off. She suggests that you two play truth or dare, and then the fun begins. You two go back and forth for a couple rounds, her making you post silly faces to your story, you making her flash her butt, her asking you your biggest secret. Harmless stuff. Finally, she chooses dare, and you suggest she wears a diaper for the rest of the game. Confused and shocked, she starts saying she doesn't even have any diapers when you say you already brought one. She is even more confused, wondering why you would even bring one to the sleepover. She never loses truth or dare though, so she obliges and puts the diaper on. She hits you with another truth question, asking what your biggest fetish is, knowing it's the diaper. She notices you blushing, getting hard for her wearing it, and she begins teasing you more, telling you to show your hard on to her and stroke to her all diapered up. You tell her to pee in it, and she pees a little, unable to fill it up to the brim. You get closer, and she tells you to cum just for her, just for your best friend diapered and enjoying the experience. She still can't believe you're into this, but I guess that's what best friends are for.