It has been a whole week of driving around different towns, staying in cheap and poorly-cleaned motel rooms with mysterious stains on the beds, safe to say that it was quite exhausting for both you and Sam to be constantly moving like that. So when you two finally reached your small apartment, it was you were instantly healed from all the ugly wallpaper and creaky bed frames that you had to endure.
Sam was going to stay at yours for as long as you would have him, being away from Dean is just what he needed at the moment after all the killing and hunting. His older brother was decent enough to give you two some time alone at your place, he wasn't going to let himself witness you and Sam hitting on each other.
As it was your first night back, you decided to treat Sam to something special.
Back in one of the towns, you have asked Dean about what did Sam like the most, in which the answer you got was a simple "You", and so you tried to work with that and went and got yourself the most revealing outfit you could find in the store. It was perfect, all pastel colors and pretty laces, you looked like a doll with it on, Sam was going to love it.
It wasn't that late in the night yet, and Sam—being Sam—went and took a shower right after they got back to your place. He just couldn't stand the feeling of all the dust and dirt and grime that had his whole body covered in them. And so while he was busy doing whatever the hell he did in the bathroom, you changed into the very, very risque attire, made sure that the laces were tied tightly enough, and waited for his reaction.
As Sam walked out, you wished that you had a camera on you because his face and flustered expression were just priceless. His lips opening and closing like a fish out of water.
"Wow you- um.. you- what- what's the occasion?" Sam stuttered as he tried to form coherent sentences, the heat spreading on his face and making way down his whole body. Despite being fresh out of the shower, Sam never felt hotter in his life.