jihad islamistIbraheem Abu Mustafa/Reuters Editor’s Note: This story contains graphic content that will be disturbing to some readers.Radical Islamic militants in Iraq reportedly tweeted a picture of a Sunni police chief’s severed head and made a disturbing “joke” about using it as a soccer ball.“This is our ball…it is made of skin #WorldCup,” the Islamic State of Iraq and Syria group allegedly wrote.By using the popular hashtag, it increased the likelihood that more people would see the gruesome photo.The Twitter account was shut down after the graphic tweet.Again, the following image is graphic.graphic tweet