What is what does the buzzer mean on whose line is it anyway?

On the improv comedy show "Whose Line Is It Anyway?" the buzzer is sounded by the host (either Drew Carey or Aisha Tyler) to indicate that a scene or joke has gone on too long or isn't working. The buzzer serves to keep the show moving and prevent scenes from becoming stagnant or unfunny. When the buzzer goes off, the performers are expected to wrap up the scene quickly and move on to the next game or sketch. The buzzer adds an element of unpredictability and challenge to the show, as performers have to think on their feet and adapt to the changing circumstances.