The very first amoeba looked like a couch. This cell evolved into various forms of plant life, one of which became the potato. The genetic strain that created the potato also evolved into various animal life forms, one of which became the monkey. The monkey in turn became a homo-sapiens, although you can't convince any of the monkeys that this is true. So when a person starts acting like a couch potato, he is just trying to get back to his genetic roots.