swindler or con artist, untrustworthy person
Não fecha negócio com ele, é 171: já deu calote em meia cidade.
Don't do business with him, he's a 171: he's already swindled half the town.
The slang comes straight from Article 171 of the Brazilian Penal Code (Decreto-Lei 2.848/1940), which defines the crime of estelionato — fraud: obtaining an unlawful advantage by deceiving someone through trickery or any other fraudulent means.
Sources: Código Penal (Planalto), Politize!.
Falando's Idiom Trainer teaches you to recognize idiom meanings and create sentences using them, so you can speak like a Brazilian.
