I spent more time trying to find this map than it took to get the achievement.
Multi-Player
Private Match
Select Map
VILLA - DLC
Start match
Wave-1
And "Dung" refers to being killed by the bell, not by manure.
When you spawn, you're in a small court yard with a bell above you in a stone tower. Leashing or shooting the bell causes it to drop and kill any enemies in the court yard.
You just need to run around the bell tower until there are 5 enemies with you. They don't come in very fast so you have to dodge and weave a bit until they get to you. Maybe even leash one or two into the court yard.
When you have 5, leash the bell, watch it drop and POP goes the achievement. 30 seconds, easy