A great alternative to boring sentences like "thanks, Captain Obvious" or "no shit, Sherlock."
When someone says something so obvious that it should be more common knowledge than the color of the sky.
"holy shit guys i just realized that rage against the machine is advocating against capitalism"
"in other news, the sky is blue"
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?"