There are so many definitions of "chapa" provided here and here. I have no idea how to translate the word in the context of my text, which narrates the events of a young and totally green noncommissioned military intelligence officer in 1983 who has just been stationed in a tiny village to interrogate and kill presumed Shining Path terrorists in his custody: "El capitán se le acercó. —¿Qué tal? —le dijo. —Bien, mi capitán. —Ponte una chapa. —De acuerdo, mi capitán. —¿De dónde eres? (etc.)" Note: "chapa" is italicized in the source text, for some reason — presumably because the way it is used here is a colloquialism local to Perú. Any ideas? Happy New Year!