Okay so I've been looking for this fic for over a week. I'm 99.9999999% sure it's on spnkink-meme or spn-blindfold but I can't seem to find it and it's driving me crazy.
To start off with, I'm 95% sure that this was J2. If not, then it's definitely AU because this take place in a classroom setting. So (pretending that this is J2) J1 and J2 are in a established relationship. J1 is teaching a class about pornography (though I think they say they called the class something else so they could teach it at the college). J1 needs to show his class in-depth how everything works so J1 asks if J2 will come to his class to give him a hand. J2 agrees. At one point they do end up fucking in front of the entire class.
There's one scene that I remember vividly and that's just of J1 or 2 dragging a mattress into the middle of the room. Also, that there are two OC's (both boys) who are dating. One of them is taking the class because he wants to get into porn. The other one is taking the class because his boyfriend is.
I could be wrong, but there may have been another person who did J2's job before J2 showed up, but then he quit or something (I think maybe he went to model nude for an art class?) and that's when J1 asked J2 to help out with the class. Though, I may be mixing up 2 stories with that one.