It is an Americanism that was widely used in Argentina with the initial sense that the beneficiary in a discussion, business, game or similar gives it for concluded and without possibility of claim. But over time the interpretation became more lax and ended up exclaimed by swindlers or scammers as "Fuck you!" Its origin is in a Spanish phrase misheard as it is "pelillos a la mar" ("settle a confrontation by common agreement and without rancor"), which was understood in South America as "pelillos a la madre", its meaning was misinterpreted, and it was adapted using: "pelito" instead of "pelillo" and "para la vieja" by "para la madre" eliding the preposition.
