Various linguistic ramblings:
I hear this all the time when my wife converses with other Nicas, "iNo me fregés!" It finally dawned on me that it means, "Don't mess with me!", or, "you're kidding!" "Esta fregando con la llave," "She's messing around with the key."
"iHijo de su madre!" I guess that's the family-friendly version of SOB, but it's not like my wife restrains the language otherwise. iHijue puta! Rolls off the tongue as easily.
I saw a guy riding in the back of a pickup with a baseball cap emblazoned with, "iDale pues!"