When one's friend is jealous of his/her hat, so he steals it and hides it inbetween a Mini Melt machine etc.
Pat had a real cool Whitehall baseballhat, but his one friend Christian was very jealous of it. So christian stole it and shoved it in between a mini melt machine at the mall. The third friend Christopher was Mr. Innocent! Christian was the hatblocker!
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?"