Far Cry 3's The Good Stuff achievement/trophy requires you to "craft a special syringe." This can only be done once you've collected 30 relics, which appear on your map as white vases. They're not that hard to find and once you've got 30, a new category under Syringes will unlock in the Specials menu. The first one is called "Untouchable" and it'll cost you 5 gree leaves, 5 blue leaves, and 2 white leaves. Once you've crafted it the achievement/trophy will pop.