A funnel used to fart into peoples mouths, generally any kind of funnel placed into someone's mouthand then farted into, generally it is used on the first person who parties out early.
When someone places their lips tightly around another persons stink trumpet and they fart in your mouth and you swallow that fart like It's grandma's apple pie. Then you belch it back up and blow it in someone's face.
Lester: HeyJim I need you to give me a good Ol' fart funnel, my grandma pissed me off and now she's gonna regret it.
Jim: say no more my friend! Get ready to suck this fart.
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?"