Genuinely forgetting to wear underwear, then dining at a localrestaurant. Then you become aware your penis is hanging out and in full view of anyone looking in your direction.
Bro, I was at lunch and realised I was doing a Dirty Stefanos when my dick was just hanging out because I forgot to wear underwear..
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?"