The Ninja Shadows were a phenomenon in Club Penguin, which appeared in several rooms. They could also be seen in the Dojo during the Halloween Party 2008. The Ninja Shadows appeared for a split second during the Lightning Storm in the Halloween Party, and many players were often trying their best to capture a snapshot of the shadows. They seemed to appear when lightning struck and at the moment that the whole Dojo turned black.
It was secret in the Dojo during Halloween Party 2008.
When you dance while wearing the ninja suit, you actually disappear into a shadowy form instead of turning completely invisible.
In November 2008, there used to be ninjas jumping from the sky and bouncing away. This one used to come every 5 minutes at the Town, HQ, Ski Hill, and the Plaza. After Card-Jitsu was released, these 'mysterious penguins' vanished. The ninjas found at the Lighthouse and Ski Lodge are still there.