look up any word, like half chub:
 
3.
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 Tom today during Ultimate Frisbee? That guy's freaking amazing!

Katie: -nods- He's so ninjastic!

--

Ashley: -pulls out a pencil- Shing! -starts to draw- Whoosh, whoosh whoosh...

Travis: Ashley's so ninjastic when she's drawing...
by Brittyn May 14, 2009
 
1.
Ninja and fantastic put into one. Being as fantastic as a ninja.
Behold my kunai! I am ninjastic!
by YumeChan February 21, 2004
 
2.
using acts or carrying out a lifestyle that someone may say is "ninja" (being super sneaky, cat like reflexes,etc.) this term can be associated with everything ryan weiskopf does and says.
JOE-hey man, today i was thrown into oncoming traffic, but i dodged every single car.
JERRY-dude. thats pretty ninjastic.
JOE-i KNOW, right?
JERRY-wanna go watch date my mom?
JOE-yes.
by ryan w.e.i.s.k.o.p.f. February 27, 2009
 
4.
(1) adj. Hybrid of Ninja and Fantastic. Describes one who is fantastic and a ninja at the same time. (2) v. the display of certain skills or abilities which are esentially 'ninja' in every way imaginable (i.e. possessing high skill-level abilities that border on super-natural, being super sneaky, omnipresent, smarter than Alabamians, perfecting the superpunch, agility, stealth, cat-like reflexes, etc.) Commonly used to describe Lu and her unmatched ninja skills; when performing an extreme act of ninja greatness AmyLu has been known to describe her mood as NINJASTIC.
Lori: OMG, WTF! did you see how awesome and sexy it was when Amy released the Ninja Cat on Joe that night?

Brook: HECK YES I DID, wow... Amy is TOTALLY NINJASTIC!

Joe: Josh man, did you hear about Amy spraying Chanel in my beer for months?

Josh: No I was busy being an asshat, but that sounds pretty Ninjastic of her...

Lori: Hey Amy, you seem like you're in a ninjarific mood as usual, you must have done something really awesome and ninja today?

Amy: Yeah, it's not my fault I'm awesome, so I'm just feeling pretty Ninjastic...
by L0o August 19, 2009
 
5.
An oxymoron using ninja and fantastic seeing as how ninjas actually equal teh sux
man ninjas do certainly suck a whole lot... i cant believe some one actually came up with the word ninjastic
by not_michael October 12, 2004