A large volume of human excrement that 'fills the pan' and pokes up out of the water. So named as it resembles a dark chocolate version of the large bodies of ice that scatter the oceans in the polar regions. The majority of its bulk being underwater, a solid lump protrudes into clear air space and fills the room with its noxious odor.
"Dude, after that stack of wings and pizza last night, I just laid down an iceturd."
"Excuse me your honor, I'm unable to address parliament this afternoon, I have a desperate need to launch an iceturd upon the high seas." (taken from British prime minister Tony Blair's private diaries)