The Ultimate Crossover
The Doctors were sitting in their lounge chairs behind This Time Round, supervising their companions in the '3rd Subjective-Time-Period Volleyball the companions of the second 4. The teams were evenly matched, with Susan serving on one side and Grace serving on the other.
As the game reached an end, with victory going to the 'Originals' - again - K-9 rolled out of the door with a tray of drinks balanced on his back. As one, everyone shouted "KOOL-AID!"
Just then, a large, glass pitcher with arms and legs broke through the back wall and bellowed, "Oh Yeah!"