OI OI Ask Urban Dictionary about OI OI Share definition Flag A loud greeting to be given to freinds in public areas, the louder the better in order to make passers by shit their pants. Me: OI OI!!!!!!!!!!!! Neil: OI OI!!!!!!!!!!!!! Passer By: <Sqeulch> OI OI by Wise Man October 10, 2003 0 0 OI OI Merch Get the OI OI mug. Buy Now — $32.95 See more merch