Background: London rhyming slang. Named after J. Arthur Rank, a twentieth century British film producer.
NOUN: Masturbation, or Wank. Rank provding the requisite rhyme.
NOTE: Besides the obvious rhyme origin, this piece of slang may come from the famous opening of Rank's films, which depicted a muscular man in a Toga banging a gong.
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.