Oye-yoy-yoy, man oh man,
“Oi” is used to express surprise or can be uttered when someone makes a mistake, like “whoops”. It is used in lots of countries like England and Sweden.
As in this case though, three “oi’s” in succession can be used after a diss, (just like Eminem does here) it would be equivalent to going “oh damn”, “oh shit”, “snap” or whatever.
To help improve the meaning of these lyrics, visit “So Much Better” by Eminem Lyrics and leave a comment on the lyrics box