Originally (early 70s or so), a standard cliched response to the question "What's up?". Then, in the late 80s/early 90s, a new generation misunderstood the origin of the response so that it soon became the standard reply to similar questions, such as "How ya doin'?" or "What's goin' on?"
Dude 1: What's up, man?
Dude 2: You know, nothin' but the rent.
Dude 1: Hey, man, how you doin'?
Dude 2: Aw, nothin' but the rent, man.
Originated as a Black American synonym for 'man', taken from the French word for man/men,HOMME (pronounced 'ohm' ). It is unclear if the mispronounciation was intentional originally. Then,became misheard or the origin misunderstood, by both blacks and whites. For example: 'Holmes', 'Homes', 'Homeboy', etc...
Hey, Homme, you got 5 dollars I can borrow?