Playing Chicken in my Sleep

Playing Chicken in my Sleep is an undiscovered challenge in Hayter's Folly, an area in the Captain Scarlett and Her Pirate's Booty DLC.

Strategy
This challenge is achieved by killing both Sandman and The Big Sleep before killing any of their minions. You can accomplish this by sniping either of them for the first kill, and then closing in to kill the second. It would seem that sniping The Big Sleep first is the best strategy, since he is the tougher of the two.