So, there was this fic i read a while back in which Dean sells toys of THAT variety, and Cas doesn't know what to use or something. All i know is that Dean takes him to the back of the store and teaches him how to use various toys. I don't remember who was bottom or top, but i *think* Cas was GIGANTIC. Or, well-endowed.
And i think Dean liked that.
Sorry if that's too little detail, but that's all i remember.