Boo

Boo is a phenomenon often used to express surprise or to encourage a response, commonly associated with playful fright. In online contexts, it's also a term for dislike or disapproval, such as booing at a performance. The term is widely recognized in popular culture, often depicted in movies, cartoons, and literature, where characters might say "Boo!" to startle someone. Additionally, “Boo” serves as a term of endearment or affection between close friends or partners. Overall, it encompasses a range of emotional expressions, from playful teasing to disapproval.