When you have friends and they are really cool (and or your "pookie") and you want to say they slay (are cool) and they eat it up every time (they win and aren't losers every day) , and they are Delicious.
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.