The word 坐牢 is formed by combining two characters to create a metaphorical image: 坐 (zuò) means "to sit", and 牢 (láo) originally means an "enclosure" or "pen", such as for animals. Together, they visually depict the concept of being imprisoned, one is made to "sit" within the "enclosure" of a jail cell, thus conveying the idea of serving a prison sentence through this concrete, action-based scene.