Someone that is so thick skulled that you couldn't pound an intelligent idea into thier head with a hammer. A person with no clue how to function in society & therefore is a nuisance to everyone. Boundless incompetence. This word is believed to be derived from the term hilljack.
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?"