a stroke of luck, incredible luck
Achar dinheiro na rua é uma égua de largura.
Finding money on the street is a real stroke of luck.
Northern Brazilian slang built off égua, the Pará-Amazonas all-purpose interjection ('wow!'). Égua de largura literally evokes a wide-bodied mare and intensifies the exclamation: a piece of unusually big luck.
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.
