Remember the character in the first season of the TV show "The Walking Dead," who was handcuffed on a rooftop and had to cut off his own hand with a hacksaw to escape a horde of cannibalistic zombies? Well, that actually sort of happened in real life, though there weren't any undead involved.
In April 2003, 27-year-old Aron Ralston was climbing in Utah's Blue John Canyon when an 800-pound (363-kilogram) boulder fell on him, crushing his right hand and trapping him. After struggling unsuccessfully to chip away some of the boulder with his multi-tool knife, Ralston tried to rig a pulley with his climbing rope to tug the rock away from him. That didn't work either.
Finally, after being trapped for six days, Ralston realized that the only way out was to amputate his crushed arm. Even though the pressure of the rock had cut off some of the circulation and he no longer had any sensation in his hand, cutting through the nerves and breaking the bones with his knife was "a hundred times worse than any pain I've felt before," he later recalled to National Geographic News. Amazingly, he later resumed climbing thanks to a special prosthetic hand with a built-in climbing pick [sources: Benoist, Ralston].
Ralston's story was recounted in his book "Between a Rock and a Hard Place" and the movie "127 Hours."