the airborne mutation of the terrible cranial disease yeulgeis
carriers generally deny any form of illness, and this denial causes the yeulgeis to mutate and spread.
-resembles black mold, clings to refrigerators, and household appliances, and anywhere where a host is in contact.
'LOOK! the black angus yeulgeis!!'
'oh no! cover your mouth, or the black angus yeulgeis might get cha, har har har'
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?"