Recently I was reading some of L. Sprague de Camp’s science fiction stories set in a future in which Brazil has become the dominant power on Earth, and so Brazilian Portuguese is the lingua franca on Earth and in the spaceways. In some of the stories, Tamates! is used as an exclamation of exasperation, frustration, anger, etc., in much the same contexts that Damn! or Shit! might be uttered.
Does anyone know if this is an exclamation used in present-day Brazil (or Portugal)? If so, what does it literally mean? ("Tomatoes"?) Is it some kind of minced oath?