Mad money, also known as emergency money, is a term used to describe a small amount of cash that a person may carry with them for unexpected expenses or impulsive purchases. There are several other words and phrases that can be used as synonyms for mad money, including discretionary funds, funds for incidental expenses, pocket change, or spare change. These terms all refer to the small amount of money that a person may have at their disposal for discretionary spending or unexpected needs. Regardless of the terminology used, having a reserve of emergency funds is always a wise financial choice for unexpected circumstances.