An entity that cats can see but humans can't. Cats are driven insane by them and must destroy them. Whenever you see a cat attack nothing with an insane fury, it's probably a greeble
Random bumps, extrusions, and hills and valleys, usually planar. Used in 3D modeling and animation to addinteresting detail, like that on the surface of the DeathStar.
The act of hugging, squeezing or smothering something that is overly cute and/or cuddly. (What the abominable snowman did to "George" Daffy Duck in "The Abominable Snow Rabbit" Looney Tunes cartoon).