This bug appears when you move a boat with two Zombie Pigmen, hit them, and then breaking the boat. It sometimes happens, so, it's possible that there are some chances that the bug doesn't work.
The baby Zombie Pigmen don't sink into the blocks, so, it only works with adults.
How to produce:
- Spawn a Zombie Pigman
- Put it on a boat
- Use the boat to move around
- Get out from the boat
- Spawn an another Zombie Pigman on the boat
- Push the boat
- Hit the two Zombie Pigmen
- Break the boat.
Result: The two Zombie Pigmen sink into the block.
Note: The Zombie Pigmen sink in one block, but they can't get out.
