noun: A person who listens or joins into the conversations of people unbeknown to him.
verb 1: to scrape, or scrape in, involving yourself in other peoples discussions.
verb 2: Scrape, or Scrape out! is said to scrapes when they scrape in. It then grew into generally meaning "go away". Can be used in lot's of situations
"Gerald is such a scrape, we were chattin about Laura and he joins in like he knows me"
"Bob totally scraped into their group, he's a twat"
jim: *punches Mark*
Mark: "Scrape out you dickhead!"