Not only is taro an important staple in the Palauan diet, but a serving of taro is essential at any feast and taro is the essential food in a food-money exchange. Its importance is recognized in this idiom.
To marry or have intercourse with the wife of one's brother. There is a potential reciprocation in which money may go from an elder brother in return for food and service from a younger brother. Once established, particularly where the younger couple have children, a cycle of this type may continue after the younger husband has died. Marrying the wife of a deceased younger brother, then, will interrupt such a cycle. Similarly, sexual relations with this woman may jeopardize the cycle.