Somewhat OT, but that is generally referred to as a duck[1], and it _definitely_ has its uses.
> The artist working on the queen animations for Battle Chess... did the animations for the queen the way that he felt would be best, with one addition: he gave the queen a pet duck. He animated this duck through all of the queen’s animations, had it flapping around the corners. He also took great care to make sure that it never overlapped the “actual” animation.
> As expected, he was asked to remove the duck, which he did, without altering the real Queen animation.