I grew up, like some, playing “cops and robbers” with other kids in the neighborhood. We never called it good guys and bad guys or policemen and thieves or anything else, just “cops and robbers,” and we never reversed the order of the two words. I'm wondering if there is an equivalent fixed phrase in other languages for this childhood pastime. (By the way, American kids played "cowboys and Indians" too...pretty similar, and pretty politically incorrect, I might add! ) In Esperanto, to play cops and robbers is ludi «rabistoj kaj ĝendarmoj». Notice that the robbers come first in this fixed phrase and the cops come second, the opposite of the English version.