The phrase "were mad about" can be equated with feelings of anger, frustration, irritation or annoyance. The antonyms for the phrase include emotions of calmness, serenity, peace or contentment. When people are "mad about" something, they may be excessively passionate or deeply involved with that particular subject. On the other hand, when they are not "mad about" something, they may be indifferent or not as passionate about it. The antonyms for being "mad about" can also encompass different emotions such as joyfulness, happiness, excitement or elation. Hence, depending on the context, there can be several antonyms for the phrase "were mad about.