You just got moved up to a higher grade of sausage, is all.”
Infatuated with Vikia the sniper, O-Dog is more than competent with precision-rifle weaponry. He competes with Duke to get Vikia's attention, almost always unsuccessfully. He deems newcomers not as meat but simply as a "higher grade of sausage."
O-Dog spends a lot of time shooting at beer bottles on an opposite building with his .32 hunting rifle, but isn't the most accurate rifleman (he shoots at the same place every time). When he's not doing that he just walks around Uptown.
Interactions with the player character
Due to the fact that he possesses strange meat and refers to the player and other humans as "meat" and "sausage", it is implied that he is a cannibal.
Behind the scenes
His name and proclivity for referring to people as meat products is a reference to Pittsburgh's landmark restaurant in Oakland (Uptown in game, where O-Dog is located), Essie's Original Hot Dog Shop (shortened simply to "The O" by locals). Hot dogs from "The O" are referred to simply as O-Dogs, hence his name.