Claptrap's Secret Stash is a mission in Borderlands 2
If you're willing to jump through a few (hundred) hoops, Claptrap has a Surprise for you!
Rewards: 346 XP, $320
Talk to Claptrap
Collect brown rocks
Pilfer Lost Staff of Mount Schuler
Defeat Destroyer of Worlds
Turn In: Claptrap
Where is Claptrap's Secret Stash?
The stash is in the container right across from where Claptrap is standing. Set mission to trackable to see the waypoint.
Mission Briefing (SPOILERS)
Claptrap: You helped me reach Sanctuary, minion, and for that you deserve a reward. I have a secret stash hidden very very far away from where I currently am. In order to find it, you have to perform a series of devious challenges. First, collect a few brown rocks for me. Then, defeat a bad-ass Skag. Then, go for the lost staff of Mount Schuler. Then, you should bring me the head of the Destroyer of Worlds. And then, you should dance for my enjoyment. Let me know when you are done with that job.
Mission Debriefing (SPOILERS)
Claptrap's incompetence granted you access to his secret stash considerably earlier than expected.
Claptrap: "Congratulations! You successfully subverted my meticulously planned challenges! Why don't you go check out the Stash!"
Claptrap's Secret Stash
The stash is a place to store items so that all of your characters can access them.
You can use it for twinking items between your characters