As a longshoreman I don't have a steady job waiting for me every day (or night if that's the shift I choose to work). So before I actually head to work I need to "peg in." This means I have to show up at my dispatch hall to place my peg (a small cylindrical piece of wood) in the job board to indicate to the dispatchers that I am there and want a job. Then I wait my turn to pick my job from the dispatcher for the day. The board is a Plexiglas window which holds each longshoreman's name and registration number as well as a place to put a peg. Once it's my turn to pick my job and then have picked, the dispatcher knocks the peg out signifying that I have taken a job.The names are organized into rows just to make things easier for everyone to see. As long as a spot is open on the board, one is able to move their name to the spot. This way, when it comes time to pick jobs, you will be working with your friends and hopefully avoiding people on your shit list.
You aren't guaranteed a job when you peg in. Each day there is only so many available jobs. Longshoremen are responsible for the movement of cargo on the docks. So when businesses around the world are shipping fewer goods, we see less work. Some parts of the year it's not uncommon to only work three shifts in a week. Other parts of the year we work six or seven shifts a week. Work is given out in a linear fashion, meaning that if the person before me on the board is pegged in he will always get a job before me unless he got the last job the day before. Say there is not quite enough work for me today, and the master peg (which rotates through the names) stops in the person before me. That day I wouldn't get work, and the next day I would be the first person to get a job and also have my choice of the best jobs available that day. In this way we each get a fair (or as fair as possible) chance to get a job. Of course this system isn't perfect and if everyone gets a job ("the peg spins") for several days or weeks, you could end up getting last pick each day.
Fortunately, we also have the option to not show up for work (or not "peg in"). This has its benefits and disadvantages. There are however minimum hours requirements that need to be met. If you want more vacation hours or benefits you also need to work so many hours. If we feel like we need the money we can show up every day for work. If we want to take a long weekend to go on a little vacation we can do that. If we just don't feel like going to work for whatever reason, be it that we don't like the job we will get, or we want to hold out for a different shift where we are closer to the master peg. We also don't have any reliable way to know how much work is going to be available for the next coming days, so skipping a day could mean that the next day you come in you won't get a job because of a lack of available work. Most jobs are one day. Sometimes a job will be "called back" for a day or two, meaning that if you take that job you will have a guaranteed job for today and however many days the job is "called back" for. There is a lot of uncertainty in the life of a longshoreman but I know most of my coworkers wouldn't trade the job for any other.