> If it is my lunch it can be divided, if it is yours then it cannot
Two men habitually trapped fish in the same region of the lagoon. One would occasionally ask the other to join him at lunch, the other would always refuse. One day the man who refused arrived with no lunch. When the usual invitation was extended the man refused, saying that, anyway, he had no lunch. The invitation was insistently pressed until the reluctant one gave in. As they split the taro between them the one who shared made the above statement. The idiom is a mild rebuke of a retentive person