Not the Bees!
Rare9.3%ObjectiveOptionalAnywhere
Fire a Bee Gun while wearing a full set of Bee Armor.
Both pieces come from Queen Bee (Sting Operation): the Bee Gun is a drop, and Bee armour crafts from her Bee Wax. Put on the full three-piece set, fire the gun once, pop. You'll likely have both from the same couple of hive runs - a tidy little combo achievement on the way past.