A massive poo that often results in frosting the bowl when flushing on later model residential toilets. To truly be defined as an iceberg dump, at least 10% of the poo must rise above the surface of the water. General limited to peeps w/ high fiber diets, an audible "YEEEEEAAAAAHHHHH!" often accompanies the iceberg dump.
Dude, I was dropping anchor and due to it's massive size, this iceberg dump was broken in half upon flushing and it totally frosted the bowl!