Despite the (relatively) widespread and casual use of the word, its origins are not entirely benign. The word "obroni" derives from the word "Abro fuo", which means trickster, "one who frustrates" or "one who cannot be trusted".
It is possible that the word arose during initial contact between the Ashanti and Europeans. Coincidentally, the word for "white person" used by the Ga (another tribe in Ghana), is Blofonyo (or Blofo) for short. This word in the Ga language, similarly derives from "Ablo fo nyo", which again means "one who frustrates", or a trickster in the Ga language.