A threat for surprise retribution at a later date for an earlier transgression that usually results in the instigator missing teeth. Similar threats include "watch your back" or "you'll get yours". The notion of the saying is that retribution will happen suddenly when the instigator least expects it, such as sleeping and their teeth are placed under their pillow. The saying is otherwise used broadly to mean any level of revenge.
Someone does another person wrong or victimizes them, the victim may say "Watch yourself! You're gonna get a visit from the tooth fairy!"
Or used to dispel concern by others that retribution is going to be made "They're gonna see the tooth fairy, don't worry about it."
The act of defecating into the pillow sheet of another person, due to extreme aggression, hostility, rage, or an attempt at a very funny practical joke.
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?"