The term 'boos' is a term used to describe a variety of negative reactions, such as hisses, scorns, jeers, scares, Halloween, and CATCALLS. Hisses is a sound made by a snake or other animal, and is also used to express disapproval or contempt. Scorns are expressions of contempt or disdain. Jeers are mocking or derisive remarks. Scares are sudden, intense feelings of fear or anxiety. Halloween is a holiday celebrated on October 31st, which is associated with costumes, trick-or-treating, and superstition. CATCALLS are loud whistles or comments made to express disapproval or to attract attention. All of these terms can be used to describe the negative reaction of 'boos'.