1. play the game loot buildings and swap servers to loot the same buildings over and over with very little trouble.
2. aggro some zombies try hide in a house. They will come through the walls.
3. try dropping items in different situations, sometimes they disappear, not sure if they fall through the floor or what they do.
4. Try pressing f and running into a door that doesn't open, I have gone through the door and gotten stuck a few times.
5. Try watch towers, I have fallen off them by going through the barriers.
6. Try running about upstairs and generally falling through walls of second story buildings.. resulting in death outside the building.