Next, lift the bottom apron of the crab and pull off the top shell. Remove the gills (dead mans fingers) and discard. There is a myth that if you eat the gills you will die. This is not true. Although I am not sure why anyone would want to eat the gills, because they taste horrible, they will not harm you. The yellowish substance that is located in the middle of the crab is the crab fat, better know as the crab mustard. Many people eat the mustard and some discard it. It is very similar to steak in the fact that the fat can be the most flavorful part of the crab.
Next, with one side of the crab in one hand and the other side in the other hand, snap the body of the crab into two pieces, the left and right side. With a small sharp knife, cut the side of the crab horizontally. This will expose the chambers of meat allowing for easy removal. Do this to same process to the other side of the crab.
Next, pat your self on your back, because you just successfully cleaned a Blue Crab. (you might want to wash your hands first, because by now you are probably covered in crab seasoning)