[ponco]

In my experience, 'oi' has a few usages:

- Drawn out "oiiiiiii" and a pointed finger when someone makes a witty remark or has some kind of success. As in, "oiiii, nice one".

- "OI!" as a generic "hey!" shouted at someone to get their attention in the street.

- "oi?" with an upwards inflection to express disbelief

- Getting your friend's attention, usually followed by an insulting term like 'dickhead'. As in, "oi dickhead, watch out" when someone is trying to pass them on the street.

[AndrewDucker]

I'm pretty sure the third one is separately descended from the Yiddish "Oy Vey"

[dcx]

That's very interesting - the Chinese "oi" has pretty much exactly the same usages, down to the little details! (I'm most familiar with the Cantonese 喂 wai2, though it's not my first language)

I wonder if that suggests this is one of those universal pre-linguistic words, like "huh" [1]. That feels especially believable given the utter simplicity of the mouth sound. It's almost just a yell, in the same way that "huh" is almost just an outbreath.

[1] https://www.smithsonianmag.com/science-nature/everybody-almo...