"sideshow freak," 1916, . carnival and circus slang, perhaps a variant of geck "a fool, dupe, simpleton" (1510s), apparently from Low German geck, from an imitative verb found in North Sea Germanic and Scandinavian meaning "to croak, cackle," and also "to mock, cheat." The modern form and the popular use with reference to circus sideshow "wild men" is from 1946, in William Lindsay Gresham's novel "Nightmare Alley" (made into a film in 1947 starring Tyrone Power). "An ordinary geek doesn't actually eat snakes, just bites off chunks of 'em, chicken heads and rats." [Arthur H. Lewis, "Carnival," 1970] By , used in teenager slang in reference to peers who lacked social graces but were obsessed with new technology and computers (. the Anthony Michael Hall character in 1984's "Sixteen Candles"). geek out vi. To temporarily enter techno-nerd mode while in a non-hackish context, for example at parties held near computer equipment. [Eric S. Raymond, "The New Hacker's Dictionary," 1996]
The term yankee is mostly used in Argentina to refer to people originating from the United States as opposed to gringo which is mostly used to refer to farmers. Following the original Spanish meaning, gringo in Argentina was used to refer to non-Spanish European immigrants who first established agricultural colonies in the country. The word was used for Swiss, German, Polish, Italian and other immigrants, but since the Italian immigrants were the larger group, the word today is mostly linked to Italians  or their descendants.  It has also found use in the intermittent exercise Gringo-Gaucho between Argentine Naval Aviation and USN aircraft carriers.