Throwing Knives

Throwing Knives
Great little gift but maybe not for that co-worker that's a little sketchy. He might throw them at your cubicle/around your head.
$7.24
Via amazon.com

Ninja Pen with Sound Effects

Ninja Pen with Sound Effects
It's the classic ninja pen: a knife that goes "SHHHING!" when the tip is clicked, and the ninja ballpoint extends, ready for you to write ever-so-deadly letters.
$4.99
Via vat19.com

Ninja Barbeque Set

Ninja Barbeque Set
You'll be grilling like a master ninja in no time. The carrying bag also transforms into a slick apron. Comes with a BBQ fork and spatula (not from Spatula City) that both have sword grip handles.
$27.99
Via thinkgeek.com

Ninja Tiger Climbing Spikes

Ninja Tiger Climbing Spikes
Ninja climbing spikes to assist with climbing. These are the real thing and are similar to those used by ninja centuries ago. Don't take them to your local climbing park - they'll tear up the walls!
$13.82
Via amazon.com

Ninja Disguise Shirt

Ninja Disguise Shirt
A ninja may strike at any time. Typically they don't advertise the fact that they're a ninja, but this shirt is merely a disguise. However, you never know when a true ninja might be wearing one...
$16.99
Via amazon.com

Ninja Coffee Mug

Ninja Coffee Mug

This ninja mug has been known to bestow ninja powers upon people. If people can't see you after drinking from it, it's either working or you're finally going crazy. Maybe both.

$9.64
Via amazon.com

Ninja Cookie Cutters

Ninja Cookie Cutters

These help you make ninja cookies that will attack the taste buds! They may vanish on you and then sneak up from behind. Eat them before they get you. 3 cool action-pose designs.

 
$9.42
Via amazon.com