Pitiyanqui = Petit yanqui (in french) = little yanqui WHERE yanqui = US citizen
This word is despectively about people from other countries that live like Americans (“Americans” in US sense). I want to be clear on it: US people is not the problem but guys believing thenselves “Americans” (US citizens) while they are living (and to be from) other countries. People make a fun of them. I don’t know “properly way” of saying it: people see them like… feet-lickers? Sorry for my language barrier.
It sounds like Americans that live in America but act like they are Japanese. Or, well, they think they are acting Japanese, but all they know about Japan is what they see in anime so really they are just acting like over-dramatic cartoon characters.