This Chileanism is a variant of the Spanish phrase "me importa un pito" (sometimes exaggerated as "me importa tres pitos" ), and is a misinterpretation of "pito" in its meaning of "pico, pene", when in fact it means "pifano, whistle, who plays the instrument". Either way, it is very common to express a contempt using profane words, as in "I care a fuck", "I care about a shit", "I care about a sieso", . . . so the phrase does not lose its meaning. See import a pito and pínfano by origins .
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