It is an Argentinian tradition to eat gnocchi (potato dumplings called ñoquis in Argentina) on the 29th of each month, a habit probably introduced by Italian immigrants. Argentinians have the custom of placing money under their plate of gnocchi, to attract good luck and fortune for the coming month. 

Argentina Fact:  Don’t Give the Thumbs Up. It’s the cultural equivalent of “Up yours.” The “Ok” symbol — making a circle with your thumb and forefinger — is also considered vulgar in Argentina, so your best bet is simply a universally friendly nod.