A cross between two similar phonetic spellings of expressions: Whee, a high pitched glee; and Bwahaha, an evil and maniacal laugh. This combination results as a mischievious shout of joy. May be lengthened and/or have "hehe" added to the end of it for emphasis.
"Bweeee!"
"What are you up to this time?"
"Nooooothing."
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?"