The verb for being ninja like. Usually used to describe someone who is amazing at stealth and/or uses obnoxious ninja sound effects in their day to day activities, but makes it seem natural.
Sarah: Omigosh, did you see Tomtoday during Ultimate Frisbee? That guy's freaking amazing!
Katie: -nods- He's so ninjastic!
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Ashley: -pulls out a pencil- Shing! -starts to draw- Whoosh, whoosh whoosh...
Travis: Ashley's so ninjastic when she's drawing...
Mostly done in fan-art, it is the name for the humanization of any animal-like character. Most popularly done with Sonic the Hedgehog characters, and Pokemon.
Zetsu, meaning "reed flute" in Japanese. He is a ninja, a member of the Akatsuki, most often used as a spy. He has a split personality, one black and one white. He also has a Venus Fly Trap growing on his shoulders, which wrap around his head. His home village is unknown.
Pein, Konan, Zetsu, Hidan, Kakuzu, Kisame, Itachi, Deidara, Sasori, and Tobi are Akatsuki members.