1). an onomatopoeia, the sound one makes when delightfully rapidly ingesting something delicious, the context most often used is when scarfing down a delicious food, such as a cookie or sandvich.

2). the phrase is near commonplace on the internet but originated with Sesame Street's Cookie Monster

3). the sound is also used in Team Fortress 2 when the Heavy class eats a deliciously looking "sandvich" after becoming damaged and regains full health.
Cookie Monster: (while making a mess, shoveling what appear to be chocolate chip cookies into his mouth) NOM NOM NOM!

Heavy: "What was dat sandvich? Kill dem all? Good idea! Ahahaha!" (bites sandwich) Nom nom nom...
by thewhitehatpimp March 28, 2011
The act of eating or stuffing one's face with delicious snacks, treats, hot dogs, KY jelly, Man-Meat, monkey shit, etc...
-Hey are you eating my fucking KY jelly you FREAK!!
-Ohh Goddamnit Jerry!! This is the 5th fucking time!! You have to stop!!! Eat your Cheerios instead!! Fucking teething little 8 month infant!!!
by Senator-Kevin December 11, 2008
The noise my cats make when they are scarfing down their food. It sounds like a cross between the word nom and a deep growl.
I place tuna on a plate and my kitty Oscar goes nuts. He then eats the tuna in a very fast manner and makes a growling noise that sounds just like "om nom nom nom."

The nom nom nom is no joke.
by Tiny Avenger March 27, 2008
The sound made by someone or something eating.

Most commonly found in lolcats and similar macros. It usually translate as, "I am absorbed in eating this".

The phrase may relate to the sound Cookie Monster makes on Sesame Street when eating cookies.

Also "Om nom nom".
*picture of kitten asleep in food bowl*

Joe: So how's that burrito?
Jack: Om nom nom nom!
Joe: So good, then?
by Infamyanonymous January 19, 2008
1) sound made when a girl wears shorts that are one size too small and it looks like her crotch is eating them
2) action noise of eating
3) Pac-man
-"hey look at that girl..... Nom Nom Nom"

-"that looks delicious, Nom Nom Nom"
by buhagias0924 July 28, 2011
Nom nom nom - Verb
1. Eating something rapidly.
2. Eating something and enjoying it.
Holy crap! Is that cake?! Nom nom nom!
by 3rd Degree Burns September 10, 2011
The sound made by a voraphile when joyously devouring someone.
*Jane sneaks up on alice and...*
Jane: mmmmmm, alice was good...
by Chazz3233 March 13, 2009