A fun way to introduce the concept of anger as a secondary or surface emotion. We always feel something before we get angry, did you know that? And if we can label or take care of that emotion, it can help with those lovely outbursts! This concept being difficult and confusing, as well as hard to explain - this activity will give your client a visual, and can work for clients most ages (the really young kiddos might have a hard time, but even adults can relate and learn about anger as a secondary emotion).
Label each ingredient (or layer) an emotion that can lead to anger, save the piece of bread on top for anger, then tell a story about when you were scared, nervous, anxious, etc., then this led to you feeling angry. I always begin by giving an example, such as "I was driving down the street, and someone backed out of the driveway, almost hitting me, and I was so MAD! But before I was mad, I felt scared, worried, then angry". Have your client give an example, then help them layer more emotions, making then understand all of the emotions we can go through for just one incident. If they can't come up with anything, or are having a hard time with the concept, read any book where the character gets angry. This can also be a way to help them process an incident, as well as practice coping skills, taking care of those other layers of feelings before we explode!