One time, an American man called me seeking help for relationship issues with his Indonesian girlfriend. Imagine, from nowhere he'd suddenly shout at me, just asking for appointment. He made demands making sure he'll be given special arrangement or treatment. He seemed to have all his "emotional buttons" turned on that moment - all his negative energy rushing through them.
A way of understanding this type of out-of-proportion reaction is that "emotional buttons" are often unhealed parts of one's self. For example, if not being accepted enough as a person is an issue for you, simply imagining people mistreating you will send a jolt of negative energy throughout your body. And you stuff it away deep into your unconscious and hide it behind your anger or know-it-all facade.
Be aware of your unconscious, hot emotional buttons. The negative energy surging through them is a symptom or guide, showing you where you got wounded and separated from your self. These fragmented parts act out to call your attention that they have not yet been healed.