When a person has been so absorbed in what he/she believes to be true, that no amount of reality, logical or factual explanation or actual proof, to show them that their believe is 100% wrong, will convince him/her otherwise.
The acronym "tfg" is mostly used. (Especially used in political discussions)
Your logical explanation of the facts are falling on deafears, because he is too far gone!
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?"