A 4-o is another word for a fourty ounce beer. Pronounced four-o or depenting on regional origin fo-o
Let hit the sto and get a 4-o.
I was two 4-o's deep last night man was I on one.
A bottle of malt liquor or beer that contains 40 ounces.
Yo, I got cock-eyed of two and a 1/2 4-O's and wrecked my 87 Dodge.