You can start a trash pickup mission by pressing the Sub-Mission Key or by typing /mission while driving a Trashmaster. Whenever the you start the mission, five checkpoints will appear throughout the current city. You get a bonus for each checkpoint driven you drive through. If you manage to get to all checkpoints in under six game hours, the mission is complete and you get an additional bonus. Press the Sub-Mission Key or type /mission at any time during a trash pickup mission to get the list of the pickup locations.