its part of the roommate/roommates parter storyline and is a random event, itll start with a sock on your door and if you choose to go in anyway youll catch them in the act. then you have to get lucky with more rng and have the roommates partner ask you if you think your roommate followed their orders and didnt masturbate. You have to get that second thing within a week of the first otherwise you wont be able to say you caught them.