Oi music, derived from punk, with a slower beat and lyrics centered around unity. Oi is prevailent (sp?) within the skinhead culture. Band examples: Sham 69, Angelic Upstarts, Oi Polloi.

With certain nuances and under certain situations it is the Tokyo dialect (at least where I grew up in western Tokyo and eastern Kanagawa prefecture) for what can be translated as "hey, what the fuck"!

Excellent tsukkomi for when people vote your node down and you lose experience.

Repeat after me:

OI, BAKA!!!

note: in standard japanese oi just means "hey".