What if... if your sanity is low enough to attack nightmare creatures, then isntead of seeing the corpse of a player, you see a nightmare creature idling around them. When you kill it, it doesn't drop nightmare fuel and the like, but it drops bones and meat . Then you realize you were actually hitting the body of a player, uh oh :/. Picking the bones or meat up further decreases sanity, eating the emat drops it to 0. Oh, and I think standing near the bdoy of a dead player should slowly decrease sanity, and picking their dropped items also a little bit. But burying and digging a grave etc would increase sanity.