MurphOnMillerAve wrote:I wonder what would possess a sheep to do that. (That is a sheep, right?

)
To Murph,
That is a ram sheep. Male sheep are called rams and with good reason.
Sheep are the classical flocking animal. They work out a social order by head butting. This is seen most clearly in rams who back off, then charge, meeting head-to-head with a large bang. To a ram, a person is part of the flock that he wants to dominate. You should never turn your back on a ram.
I suspect the people getting rammed in the youtube videos turn their back on the rams just to become famous. "Yeah, that was me in the video. I am famous now."
To Mitch,
That was a big pig. Pigs usually weigh between 300 and 700 lbs. My grandfather had three sows and a bunch of piglets from them. He said the sows combined weight was over 1000 lbs. I asked if I could ride one. He said, "No... if you don't know how to handle them they can be aggressive."
Domestic pigs are often bred to be heavier. In 2012, a hog named Reggie set a weight record of 1,335 lbs in the Iowa State Fair’s "Biggest Boar" contest.