Rakkman is a reference to the comic book/movie hero, Batman. He is located in the fridge and is only available after or during the "Cold Shoulder" mission. To find him take the "Cold Shoulder" mission given by Scooter. Then after Laney White opens the door go through the Rat Maze until you find an elevator. Take the elevator to the top and walk towards the chest, Rakkman will appear in a small puff of smoke.
Rakkman will shoot at you whilst jumping around the room and disappearing/reappearing in small clouds of smoke. He also has the ability to summon numbers of rakks to attack you. Although not a difficult boss to defeat. Rakkman can become very frustrating due to his fast movements.
Among the ammo, money and standard weapon drops, some players may be lucky enough to come across Rakkman's legendary weapon. Rakkman has the possibility to drop the Gunerang. This Legendary pistol is very rare due to the fact that Rakkman is a difficult boss to farm, because of the long distance you must travel to reach his lair.