(simulates noises made while eating)
you: om nom nom(everybody laughs and the silence is broken).
Me: I dont know.
Friend: Oh my god it is.
Raccoon: OM NOM NOM
Second person: "Did you see how Aki was om nom noming that leaf cupcake!"
"Om nom noms" is the present progressive of "to nom" which means "to eat with enthusiasm." Therefore, "om nom noms" means "eating with enthusiasm".