I remember in GTA 3, the city had... "services" available. You could pick up these "propietors" and they will give you "service" in an alleyway, or your safehouse, or wherever.
I thought this was removed from LCS, but I managed to pick up a hooker today and drove them around. Trouble is, I can't get the car to shake. I don't think you can actually do that part in the game.
If anyone DOES know how to get that to happen, please let me know :P