[glatt]

I read somewhere recently about why the McRib makes limited appearances at McDonald every once in a while.

Think it's some elaborate marketing thing? Limited supply for a special item? Nope. It's simple economics. When pork prices go down every few years, McDonalds buys a bunch of pork, and grinds them into McRib sandwiches. When pork prices go back up, they stop selling the McRib. That's it.