in volume terms?

on another board guys are talkign bout the fine hobby fo alcohol consumption and they're like: yeah I drank a 5th of jack last night and one time I done X amount of 5ths of vodka....

speak english and tell me what it is in nice metrics. (that's ml for the mentally challenged of us)

what does an ounce convert to too? I'm trying to build up a cocktail port folio but everything I've came across is in ounces.