 Idioms for today. Fill in the blank with the correct word. When the cat's away, the will play. Children, dogs, mice, mouses. The answer is, when the cat's away, the mice will play. What does it mean? Think about it for a few seconds. Meaning, when the boss, parent, teacher, cat is gone, the employees, children, students, mice will be free to do whatever they want. When the cat's away, the mice will play. To learn more about this topic and other idioms, see video at link. Or check out our websites for more free English learning resources.