scrape- to intrude on someone else's private conversation when they are not wanted. If someone is known to 'scrape' often and does it many times they become known as a scrapegoat. Therefore when that person tries to start conversation with a group of people, without actually scraping somebody will tell them they should "scrape out". This mean that anytime the person known as a scrapegoat they are 'scraping even though they might not be, its just everybody takes joy in calling them a scrape.
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.