Claiming the Goblish Tongue  

This quest is initiated by examining a Goblin Territory Marker. The reward for the quest is giving you the ability to speak the Goblin tongue.

There is a quest NPC in the zone who only speaks goblin (Janitor Zolbuk), and the Golden Efreeti Boots also requires you to speak goblin.

Once the quest has been opened you will need to obtain 7 more Ancient Territory Markers and examine each of them. These are randomly dropped on goblins in Runnyeye, The Enchanted Lands, The Condemned Catacomb, Nektulos Forest, Permafrost, Everfrost and Lavastorm.

Your reward is an understanding of the Gobish language. Now you can understand when they're cursing at you.