If you’re into a bit of extreme writing, you should always have this pen at your side. Although butterfly knives are illegal, you can do all the cool tricks and get into none of the trouble with this Butterfly Knife-Styled Space Pen. It is capable, according to Think Geek, of writing under extreme circumstances. It can write underwater, upside down and in space. Just try not to jab anyone’s eye out when you’re practicing your fancy tricks with the pen though. You can purchase it on Think Geek for $34.99, which is a bit pricey, but it is a space pen after all.