A black poop?
Go see your doctor ASAP!

Black, tarry stools (poop) with a foul odor can be the result of something benign, such as eating certain foods or taking iron supplements. A serious cause of black stool would be internal bleeding. When the black color in stool is from blood, it is known as "melena." The dark color indicates that the blood has been in the body for some time, and that the bleeding is coming from higher up in the gastrointestinal tract.