An internet simplification of the phrase, "I know right," due to the misinterpretation of the words spoken with haste.
Better known as, "The rock of knowing" with the suffix of "-ite" that resembles the names of stones. (i.e. Labradorite, Malachite, Granite, Angelite, Azurite, etc.)
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"