Not fitness realted but funny?

So I had to call the plumber today. It seems the men's room toilet was pretty backed up. I sent Mailbox in there armed with a 6 foot snake and he came out an hour later sweaty, disheveled and beaten.

He said that he gave it his all but there must be a cell phone jammed in there. We could not hear it ringing, but it was a good guess.
Derek, the world's greates plumber showed up later armed with a 40 foot snake and went to battle.
When he was done we asked him what it was. He replied :the biggest piece of shit in the world".
That is quite a boast especially coming from a plumber.
My question is, what farm animal did it?