When a drowned's trident hits a zombie, the zombie will retaliate, causing a fight with that zombie. This might also cause other zombies to attack the drowned. But if by a chance the game happens to spawn a zombie due to a fight with each other, then zombie might target another zombie, causing craziness to happen. This can happen multiple times during the process, which will cause more craziness to occur.

This is VERY HARD to reproduce, it might take a lot of tries, but when the game will spawn a zombie because of all of this, then the zombie will fight each other, which doesn't normally happen.

NOTE: This does not trigger MC-110386.