buenas
Word used all the time by Everyone
adverb • Buh-eh-nahs • Argentinians, especially those from Buenos Aires, use "buenas" as a greeting word. It means "hello", but it is shortened from regular greetings like "buen día" (good day) or "buenas tardes" (good afternoon). "Buenas" is used informally, amongst friends or even co-workers with whom you might have a friendly relationship with.
"Buenas, ¿cómo andan?"
"Goods, how's it going?"
12 out of 15 Spanish, Castilian speakers have heard this