A: Did you tell Tom that he had been dismissed from our band?

    B: Yeah. He angrily demanded an explanation but I was saved by the bell when his younger sister came in and asked him to help with her homework.

    Note: In the sport of boxing a fight lasts for several rounds separated by a short interval for the fighters to rest and lick their wounds. The end of each round is announced by a bell. So if you are in difficulty towards the end of a round then you will be saved by the bell because your opponent must stop hitting you. There is also another story concerning the origin of this idiom. There was a strange disease in the 1500s that would slow one’s heartbeat and breathing enough that upon inspection, the afflicted person would indeed seem quite dead. To avoid people being buried alive, a string would be tied to the wrist of each corpse, threaded through the coffin and tied to a bell. Anyway, this idiom is used when one has been saved by the timely intervention of something or someone, or when one has been rescued at the last second.