a. Buttsex engaged in under emotional duress or out of lack of self respect; the 'catcher' often cries in the course of the act, not because it is physically painful, but because they cannot believe they are letting this guy fuck them in the ass.
b. Any sexual congress between emo kids, especially but not necessarily buttsex.
"Emobuttsex is the best, dude! It's like how a lapdance is always better if the stripper is crying, only it's even better, since buttsex is by definition better than a lapdance. Tears make the best lube, ferreal."
"Yeh, I totally hooked up with that guy with the tight pants and Cursive shirt.... we had pretty awesome emobuttsex."