The saying is very Mexican, although it is safe to use in other countries. Unfortunately it is not used in Argentina (where I live) and I could not find a good reference of origin; the closest thing to a saying I found is "it's like Aunt Cleta's marrana, eating and putting her ear and waiting for the shell" or "she's like Aunt Cleta's marrana: in everything but mass". It is used to point out to a person who in addition to his affairs is aware of the lives of others, or who does not even deal with his own by chusmear elsewhere. There is some version for "it is like the marrana of Aunt Cleta : the cobs that are not eaten, the urine" , and it is for selfish people who harm others even if they are already satisfied (seeing the dog of the garden does not eat or let eat ). Although it doesn't contribute much, see also aunt cleta.
