After you complete the Shadow mission in GTA IV, two items are unlocked: Badman is available as a random character for a side mission and Little Jacob begins to offer drug delivery missions.

To activate the drug delivery missions, select Little Jacob in the phone book and choose the "Job" option. Jacob will then offer a drug delivery mission. There are 10 missions total located at different points around Liberty City. Some of the missions are extra challenging by adding ambushes, sting operations or timed attacks. When all of the missions are completed, 2% will be added to the game's total completion and the "Courier Service" achievement will be unlocked.

Little Jacob is one of many associates Niko Bellic becomes acquainted with in Grand Theft Auto IV. The two are first introduced via a mission from Roman called Jamaican Heat. Little Jacob is a drug dealer and speaks with a very thick accent. If Niko maintains a good friendship with him throughout the game, he can obtain discounted weapons in addition to the occasional drug delivery job.GTA4.net Characters