A situation in which a team is leading a playoff series 3 games to 1 and still ends up losing the series 4-3 in 7 games. The most recent example of this is the Cleveland Indians blowing their 3-1 lead against the Chicago Cubs in the 2016 World Series. This phrase was popularized by the Golden State Warriors, after the lost in the NBA Finals to the Cleveland Cavaliers after holding a 3-1 lead.
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?"