Have you heard the expression vender un buzón in Argentina? The Argentina Spanish expression vender un buzón literally translates to "to sell a mailbox" and means to cheat or scam someone. Similar English idioms are "pull the wool over their eyes" and "to sell someone the Brooklyn Bridge."
So, what's the story behind this Argentine Spanish idiom? The blog Significado y Origen de Expresiones Famosas gives us the answer:
"Mailboxes in Argentina, from its postal service origin until a few decades ago, belonged to the state and were placed in many areas of the street. In the late 19th and early 20th centuries, the phrase became popular in reference to astute and clever citizens of Buenos Aires trying to "sell a mailbox" to not-too-shrewd or innocent people or newcomers to the metropolis. Since then, the term means to defraud someone, or at least try, abusing the trust or ignorance of the other."
Here is an example from the Spanish slang dictionary and phrasebook Speaking Argento:
Voy a averiguar sobre los componentes de la máquina. A mi no me van a vender un buzón.
(I'll find out about the components of the machine. They aren't going to sell a mailbox to me.)