Person 1 is playing with pet rats on the sofa in his shared apartment. Unbeknownst to him, the rats shit a few drops while he is eating breakfast. Person 2, his roommate, comes home to find rat droppings on the couch, near where he usually sits. Person 2 notifies person 1, and asks that he clean it up. Person 1 removes the turdlettes from the sofa, wraps them in a paper towel, and throws them away.
2 politely asks 1 to also find some method of disinfecting the couch, because, hey, it's shit. 1 refuses, and offers that rat shit is sterile and has virtually no scent, that things like this happen all the time, and that it can hardly cause any problems whatsoever. 2 is confused at 1's refusal to do something that he sees as obviously necessary, and insists, somewhat more forcefully, that it is person 1's responsibility to clean up the mess that he made in their shared space, and do it completely. 1 refuses, citing that the couch belongs to him, and that there are virtually zero possible consequences for not sterilizing; he says that if it bothers 2 so much, he should disinfect it himself.
A twelve-hour mini feud results, with periodic bickering, subtle power plays, and some minor passive aggression. The spot remains unsterilized.
The next morning, 1 goes to the bathroom and finds that there is no toilette paper in the holder. He opens the door and mock-sheepishly asks 2 if he has an extra roll in his bathroom. 2 snickers and walks into his bathroom, gets a roll from beneath the sink, and stands outside the door. He delivers a well-placed ultimatum: 1 can have the tp only if he is willing to disinfect the couch. 1 laughs, mocks him, and accepts the offer.