An onomatopoeical adjective based on the sound emitted when something is "oh so tasty" (either through hunger or flavorological value) that one gnaws through it without regard to cleanliness or etiquette. This sort of ravenous eating will often result in an "om nom nom nom" noise being emitted from the eater.
Arthur: Gosh, I haven't eaten for days.
Dirk: Me neither. We're both starving equally.
Arthur: Look! A whole cooked chicken with side of mashed potatoes and a warm/soft dinner roll!
Dirk: We have to decide which of us gets to eat first. To be fair, we should rock-paper-scissors for it.
Arthur: Om nom nom nom nom!
Dirk: Arthur, you're a jerk. A real knee-biter.