Ever watch a movie and see a large microphone accidentally in the corner of the frame? That's the boom microphone, the one recording the sound of the scene. Boom operators (sometimes they end up in the shot too) are the ones holding up the microphones at uncomfortable angles for a long time. They will also position smaller mics to achieve ideal sound. If the dialogue is clear, that saves the actors from coming back to rerecord themselves [source: Media Match].
This is a job that requires strong shoulders and biceps, and a good memory as you have to know the upcoming dialogue and action so you can anticipate where to place the boom. Operators often go on location, spending significant periods away from home, and of course, the hours are long. But, great workers will move up the sound team ladder in time, probably faster if their equipment doesn't make a surprise appearance in the background, as it has in huge films like "Reservoir Dogs" and "Mallrats." Whoops.