There is an International Friendship Day started in the Republic of Paraguay after the Chaco War between Paraguay and Bolivia (I believe it is celebrated on the 30th of July).  There is also the "Dia del Amigo" and the "Dia do Amigo" celebrated in many South American countries including Brazil.  I'm just not sure what day they are celebrated.  The "Dia Internacional de la Amistad" in Paraguay is one of their most important holidays; in fact many Paraguayans have trouble believing that it is not celebrated elsewhere.  People go to lunch with colleagues, buy their friends small gifts and call or text everyone in their circle.