A large bowel movement that fills the bowl of the toilet so much so that the peak is above water. The bulk of the mass remains underwater, like an iceberg.
After delivering an epic food baby, Ryan realized he had given birth to a terd berg.
The tip of a piece of poo which pokes out of the water in the toilet bowl, like an iceberg in the ocean. But only this is poo, not ice. That is why it is called a poo berg.
bill: tom u r such a yung berg
tom: yea i love that rapper
bill: No, I mean u r a fag and so is he.
tom: yes, I know...(goes and jacks off to sexy can i)