Nombies are a sub-type of traditional zombies
that are wholly dedicated to nomming
on your tasty innards
(and outtards). They aren't content to simply kill you or eat your brain: any part of you that can be eaten will suffice. Generally they are tougher than normal zombies
and will often eat their weaker brethren.
Nombie: "Rwalaahhahafggh...<nom nom nom>"
You: "Oh my GOD there are zombies everywhere!"
Your friend: "Zombies or nombies? Nombies are the ones eating the other ones."
You: "I dunno, um, nombies? How fucked am I?"
Your ex-friend: "Oh yeah, you're real fucked."