1) When the muscle of one arm is pumped up due to too much masturbation.
2) When one arm is aching because of too much masturbation.
3) When one arm is aching due to the repeated performance of a task such as sanding down a piece of wood.
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?"