Playing Chicken in my Sleep is a location-based challenge in Captain Scarlett and Her Pirate's Booty. To perform this challenge in Hayter's Folly, Sandman and Big Sleep must be killed before killing any of their minions. It is worth 4 Badass Rank.
It can be accomplished by sniping either of them for the first kill, and then closing in to kill the second. Big Sleep is the tougher of the pair, and usually the most appropriate to target first.