In the film and television world, there are lots of strange terms and jargon that really don't translate off the set. One great example os the term 'Best Boy.' It's even more confusing when gender rolls and assumptions are applied to the title. So what is a Best Boy (or Girl)? Where does the term even come from?
The Gaffer - which is the electrician, and usually the head of the electrical department will call his second in command his Best Boy Gaffer. Similarly, the Key Grip, or leader of the grip department will have their own Best Boy, or Best Boy Grip. A grip, since you're wondering, is the head of the lighting and/or rigging department. There are many types of grips, such as Dolly Grips - who build and push the door frame sized camera 'cart' or dolly, or the cranes. Now it's getting complicated again. Grips, simply boiled down, tend to move things and hold things. On Union jobs, the grips are responsible for the non-electrical components - such as flags, diffusion, nets, and gobos. We'll get to these terms later in our series.
The term grip either originated from the tools that these professionals carry on them, or the idea that they were required to, 'keep a good grip on the floor," while moving giant camera gear back in the early days of Hollywood. It's debated on set and off where the term really came from.
The term 'Best Boy' though, was probably from a Director of Photography asking his gaffer or key grip to loan him his, "best guy." The name stuck, and it's been used to provide the hierarchy of the grip and gaffer departments ever since.
PS, When you're on set and you need some non-permanent sticky tape, find a grip. He'll most likely have a roll of Gaffer's tape on him, and probably a few color choices. Yes, the grip with gaffer's tape is kind of confusing, now when you stop and think about it.