Waddafak is the "word" you would use if somebody isn't making any sence, or being a complete goof canoe. I dont wanna know what the literal fucking vagina balls that you would use this "word" in. Probably in response of the most fucked updisgusting thing a friend+ might say.
"I will shove an entire gaping hairy yellow moon-sparkling cheese filled slimey constipated squirrel penis in your throat."
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?"