Big Mouth Billy Bass is a novelty singing fish that became popular in the late 1990s. It is a life-sized replica of a bass fish mounted on a plaque, equipped with motion sensors that activate its singing and movement when someone approaches. The fish is known for performing songs like "Don't Worry, Be Happy" and "Take Me to the River." This quirky item quickly became a staple in homes and offices, often used as a humorous decoration. Big Mouth Billy Bass is powered by batteries and features a realistic design, making it a memorable gift or conversation starter for many.