The phrase "take a chill pill" is a common expression used to tell someone to calm down. However, there are many other synonyms that can be used in this situation, each with their own unique connotations. For example, someone might be told to "take a deep breath" to help them regulate their emotions, or to "take a step back" to gain some perspective. Another option might be to "relax" or "unwind" in order to release tension and stress. Regardless of which phrase is used, the goal is the same: to encourage someone to take a break, calm down, and approach a situation with a cooler head.