This can be earned in 2 or 4 player Co-Op. You don't need to worry if you don't have friends as the game will automatically match you with someone! Simply have your partner grab any bounty from the vendors then place it on the table either next to the map on the small ship or the captain's table on a big ship. Now choose your friends bounty by pressing "X" on it then hold down "X" to cancel it allowing the other player to earn this.

Worth 10 Gamerscore.