At some point in a child's life they eventually make the connection that a long plastic ruler is not unlike the barrel of a gun, and suddenly maths homework gets a lot more enjoyable as they blast away at imaginary aliens between problems. The folks at Atypyk have taken that idea one step further with a pair of plastic toy ray guns that double as rulers and protractors.
On their own the pieces in this $US20 set are fairly innocuous and can easily fool a teacher into thinking they're nothing more than tools for completing geometry assignments. But when assembled they instantly become a vital weapon in your imaginary war on whatever happens to be invading your classroom at school.
There's also a simpler $US16 version that doesn't assemble and leaves a little less to the imagination. You might find it harder to sneak that version into a classroom without setting off warning bells, but between the two it definitely more looks the part. [Atypyk]