If you go to the Forgotten Shore, behind the building that houses Rasputin, there is a rock by the water that has an interesting easter egg. The criteria for for easter egg is the character you're on must have the Lighthouse unlocked and you must have a 365 Gjallarhorn. So stand on the rock mentioned earlier and use a heavy ammo synth. Now, as fast as you can, unloaded all of the Gjallarhorn rockets into the water. Once you're out of ammo, if you did it right, you should hear Dinklebot say "...this could be going better". Now head back to the tower and you should have a gold package from the Post-Master. tl:dr [spoiler]Golden Warthog[/spoiler]