 When Jones reminds Sparrow of his debt, Jack argues that he wasn't captain during those thirteen years, for a mutiny quickly occurred and he was abandoned on an island by his crew.To that, Davy Jones replies that regardless of this, he still owes him his soul, for he has been introducing himself as "Captain" Jack Sparrow during those thirteen years (and indeed, it is a running gag in the movies that each time he is called "Jack Sparrow", Jack will correct the other by saying ""Captain" Jack Sparrow").In "Leven Thumps and the Gateway to Foo", it's impossible to kill anyone intentionally in Foo; Sabine gets around this by causing third parties to take action which, unknown to them, will kill his intended victims.