Why is a Lazy Person Called a Couch Potato?

We all know what a couch potato is- a person who sits on the couch and watches TV, moving about as often as a potato. But where did the phrase come from? The story is a lot more complicated than you knew. The term was actually trademarked. Imagine that. Simon Whistler of Today I Found Out tells us the story. (via Laughing Squid)