If you've searched for an explanation to this after being offered a meat sandwich then, the chances are, the only question you're wanting to know the answer to is this:
What's wrong with it?
Relax. Don't panic. There's nothing wrong with it - in fact, it's perfectly normal. Seriously. It's okay to swallow. The Perfectly Normal Beast is a creature a little like a buffalo with a succulent, slightly sweet flavour and a long, dark finish. The reason for its uncomfortably reassuring name is not so much what it is but where it comes from. And, equally, where it goes to - The creature itself is indeed normal, but it is its migratory habits that strike people as being odd. They appear east of the Hondo Mountains, sweep in their thousands across the Anhondo Plains in a stampede that lasts six days and, well, disappear again just as mysteriously as they appeared. And then, in Spring, they do it again but in the other direction.
From Mostly Harmless, the fifth book in the increasingly-inaccurately named Hitchhiker's Guide To The Galaxy trilogy by Douglas Adams. After years of searching the universe for a planet as close in likeness to Earth as he could find, Arthur finally settled down on Lamuella and enjoyed a life of making sandwiches for the people in his village and himself. The Perfectly Normal Beast was the filling in his sandwiches, procured by the villagers by luring the beasts away from the stampede with the aid of a pikka bird.
No-one really knew where they came from and, up to a point, no-one really knew where they went to but, being as how the Lamuellans were simple people, nobody ever really bothered to ask.