The FuBar is a single cast piece of high carbon steel that looks like a prettied up hammer. One end has a hammer and a tearing, armour-penetrating beak, while the opposite end has a conventional pry bar and nail puller. You can use it to drive nails, but what it really excels in is F'ing things up beyond recognition -- hence FuBar. You hit something with the axe-like end until it's weakened, then hit again, twist to pry, and CRUNCH!
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects