A good one, as Sergei put it. Black comedy opens many tricks and opportunities for something hilarious, but it's also much easier to completely fail at it and piss off somebody you don't want to. Good black humor requires either a developed sense of tone (something like George Carlin), or punchlines/acting funny enough to afford offensiveness of the content (stuff like Filthy Frank) - otherwise, it would be both shitty and insulting.
Bill was in a terrible accident. His hand was accidentally amputated at work by a saw. The doctors decided he would be a great recipient of a new ,fully function ,voice activated prosthetic hand. Bill was all for it. The thought of living without a hand was too much for Bill. And the surgery was a complete success. Later, Bill demonstrated for the doctors the things the hand could do with his new hand. He told it to hold a cup, and it did. He told it to hold a pen so he could write. And it did. The doctors were amazed. Later, Bill woke up from a good long nap to discover that his dick was erect. He held up the sheet and stared at his erection. Then he got an idea. He said, "Hand, jerk off my dick.", in a low voice. Instantly, and almost to fast to see, his new hand reached and grabbed Bill's penis, and ripped it clean off his body!! Bill shreaked in terror as blood shot everywhere!!! Then he screamed in a loud voice, "FUCKK MEEE!!", in dismayed terror!! And the new hand, still clutching his severed penis, began to fuck Bill with his own dick!!