When I shared a house with my younger brother and a couple of friends he knocked the chip pan over and spilled used cooking oil all over the kitchen floor. If you don't know chip pans it's like a deep fat fryer, so a lot of oil all over the floor. Instead of cleaning up, he wrote a sign saying 'Beware: oil' and taped it to the kitchen door. None of us were impressed. There was a lot of passive aggression and severe hinting until we finally had to corner him at the scene of the crime and yell at him until he cleaned up. His attitude was that it was easier to just step around the oil than do any work and if we felt otherwise we should clean it. We actually had to yell at him about the importance of it being his fault. He just doesn't get the whole Golden Rule concept.
Honestly, he's an asshole.