Jack wants you to kill yourself and will offer you a huge reward if you actually do it. If not, then you simply call a hotline and you will get nothing from Jack. Head to the spot located on your map and when you approach, a Marauder will spawn and kill himself. Press the button and you don’t get any Eridium, but if you jump, then you can return to the bounty board and actually get the Eridium mentioned above.