Pocket jinglers are people who work in the advertising industry. They are responsible for creating catchy phrases and slogans that will help to promote a product or service. The term 'pocket jingler' comes from the fact that they often carry around a pocket full of jingles and slogans. Keys is a four letter word that is related to pocket jinglers, as they often use keys to unlock creative ideas and come up with new and innovative ways to promote a product or service.