Did Somebody Order a Knuckle Sandwich?
by AergisThis Achievement is completed when you reach an Unarmed skill of 400.

TIPS
-Keeping whatever mob you are skilling up on alive longer can help get you there quicker.
-Take any gear that gives you more abilities to deal more damage off. If you have any gear with pure stamina it would be a good idea to put it on in order to live longer and take less resting time.
-If you can use Fist Weapons, try using Right-Handed Brass Knuckles to increase your attack speed. They are sold in Darnassus, Ironforge, Orgimmar and Shatthrath.
-Chance of skill up are per hit.
-Killing lower level mobs gives you skill.
-You cannot gain skill from attacking mobs immune to damage.
-Area I used to skill up on was in Scholazar Basin. I went AFK hitting the Primordial Eggs, from which Primordial Hatchlings come from.

The Druid-like trees in Crystalsong Forest are self-healing and great for this.