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*
"OM NOM NOM"
Joe: So how's that burrito?
Jack: Om nom nom nom!
Joe: So good, then?
Describing something being eaten usually in a humourous way.
Someone may badly edit a picture and draw eyes mouth and teeth over it to show that the subject is being eaten. They would then write omnomnomnom on the picture.
The kittehz food.
Cat: I WANT MY OMNOMNOMNOMZ !
The sound made by a voraphile
when joyously devouring someone.
*Jane sneaks up on alice and...*
OM NOM NOM NOM
Jane: mmmmmm, alice was good...
The sound of someone eating
typically a fat
or obese person trying to chew far too much at once making the om nom nom nom sound.
"Om nom nom nom" is an onomatopoeia
Bill stuffs his face with cake, as he eats the sound resembles "om nom nom nom"