During the production of a movie, commercial, music video etc., a spring-type clothespin is called a "CP 47", "C47", "47", "peg", "ammo", or "bullet". It is most useful on the set since lights used on film sets quickly become far too hot to touch; a wooden C47 is used to attach a color correction gel or diffusion to the barn doors on a light. The wooden clothespins do not transmit heat very effectively, and therefore are safe to touch, even when attached to hot lights for a significant period of time. Plastic clothespins are not used as plastic would melt with the heat of the lights, and metal would transfer the heat, making the clothespin too hot to touch. People like gaffers, grips, electricians, and production assistants may keep a collection of C47s clipped to clothing or utility belt at all times. Hence the nickname "bullet", as so many crew members clip a number of C47s to their utility belts, much like an old west gunslinger would carry extra cartridges (which are often inaccurately referred to as bullets) on his gun belt.
When a performer is in full makeup they sometimes cannot drink from a cup so they drink from a straw. When the bottle or cup is too deep for the straw a C47 is clipped an inch from the top of the straw to keep the straw from falling into the drink.