This, as far as I recall, only relates to the game Blackball. It's not technically two shots. The shot that comes immediately after the foul is a free shot from where the ball is. This can be used to your advantage if you know that you will make the foul and want to go for a double-pool. Otherwise, it's just one great shot. The term "two-shot" comes from how many balls are required. Before Blackball, all pool games used nine balls. Two balls were removed from the rack and placed next to each other on the table to create a single pocket. Then, one ball was removed from the rack and placed next to the first two balls on the table to create another pocket. This process continued until all nine balls had been played. Since then, eight balls have been used instead. Two shots on Black refers to making two consecutive balls in a row. If you make the first shot, you must leave yourself enough time to make the second shot or you will lose. However, if you fail to make the second shot, you get another chance since it's now a free shot. This means that you can take as much time as you need to make sure you're going to shoot successfully. In general, players should never hesitate when shooting.