After getting dragged to the Elven Kingdom, talk to DogPoo in front of the Fountain of Insight to unlock this quest.
You have to find and destroy all the human banners erected in the town. They will be marked in the map so you won't have problems finding them.
1. In front of Mr. Slave's House
2. Between the playground and basketball court.
3. In front of Kevin Stoley's House
4. In the front yard of the church
5. Along the trail to the east in Stark's Pond
After destroying all banners, report back to DogPoo to complete the quest and to add him as a friend.