Anyone interested in someone who goes to a massage therapist that ends up being much more hands on than expected! Options could include things like your guy being straight and not expecting to get such a "full" service but going along with it anyway (this could also be something placed in a college setting where your guy is on a sports team and mine is the team therapist), or your guy's boyfriend could be sitting in the waiting room not knowing that the massage therapist is currently banging his boyfriend in the other room and receiving that kind of "full" service!
Slash please and there is a possibility of exploring what happens after the appointment if things click and you're looking for more than a one off scene.