Operation Kapow was a secret plan developed by Calvin and Hobbes, possibly during one of their G.R.O.S.S. meetings and detailed to the reader via a single Sunday strip which showed a map of their plan. The map showed Calvin and Hobbes taking their sled to the top of a snow hill, sledding down at high speed, and navigating through the woods to evade enemies. They would then grab a bucket of snowballs from behind the "secret pine tree" and hit Susie with the snowballs while speeding by on their sled. They then planned to make a fast getaway by riding the sled up a snow ramp, over a deep trench and safely into their snow fort. Calvin was credited as genius/mastermind, and Hobbes as consultant/cartographer.
It is unknown if the plan was actually undertaken beyond the planing stage, and if so, whether it succeeded.