Here is an expression that we use to describe a person who likes to spend their free time being lazy, sitting on the couch, and watching TV all day. These people usually do not get enough physical activity.
"I wish my roommate wouldn't lay in front of the TV all weekend. It would be nice for us to hangout, but she is a couch potato!"
So, as we begin our weekend, let me encourage you: DON'T BE A COUCH POTATO!!! Get outside and have some fun!