To masturbate furiously while sobbing uncontrollably. Often done as a joke, using the popular mimic of "jacking off" while fake-crying.
This is a tactic used to intimidate/provoke an enemy/friend, or it can be a way to vent internal despair/depression. In the worst cases, it can simply be an uncontrollable habit (see Brian, or Shewfelt).
Dan just couldn't stop giampaoloing alone in his room, after having failed his math test.
Brian started to giampaolo when he was rejected by every girl at the party.