to be running on fumes, to be wiped out
Depois daquela maratona, voltei pra casa só o pó.
After that marathon, I came home running on fumes.
Só o pó ("just the dust") is a short, modern way of saying you are completely worn out. It clips the fuller Brazilian saying só o pó da rabiola — "only the dust of the kite-tail." A kite's rabiola (tail) frays away with use until nothing useful is left, so a person reduced to "just the dust" has nothing left in the tank.
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.
