A fit of irritation, also known as a SNIT, is an outburst of anger or frustration. It is usually characterized by a sudden and intense feeling of annoyance or displeasure. It can be caused by a variety of things, such as a perceived injustice, a stressful situation, or a feeling of being overwhelmed. It is often accompanied by physical symptoms, such as increased heart rate, sweating, and clenched fists.