Kill 100 monsters with thrown melee weapons
You can throw just about every melee weapon in the game, beside brass knuckles.
To throw a melee weapon hold to aim & lock ON and then press to throw your weapon. I found that throwing blades to a lot more damage and is almost an instant kill. Also would recommend to damage the zombie(s) first before throwing your melee weapon. You can pick up the weapon you have thrown at the zombie, and keep thrown it.