demonic, ghost-like entities heard to be seen after listening to music for long periods of time, usually heavy/thrash/death metal
also: what seems to be the first real lyric in the song Ruin by Lamb of God
"HOLY SHIT last night i was listening to music when out of nowhere i was attacked by all these falaylays! they were fucking everywhere! it freaked me out!"
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.