In Japanese, when a person uses somebody else or something for his own purpose or interest, this behavior can be described as 'dashi ni suru,' which literally means, 'uses somebody else or something as his (or her) own 'dashi' (soup stock),' but this is also a typical Japanese idiomatic phrase in reference to food.
自分の目的や利益のために、他の人やものを利用する・方便にすることを「出汁に使う(出汁にする)」と表現することがあり、食品を用いた慣用句の代表例の一つである。