couch potato
From Longman Dictionary of Contemporary Englishcouch potatoˈcouch poˌtato noun [countable] NOT DO somethingLAZYsomeone who spends a lot of time sitting and watching televisionExamples from the Corpuscouch potato• Tired of watching the Grammy Awards as a couch potato?• The last thing I want to do is to share a place with a couch potato.• And nomatterhow fit you are, you're just as susceptible to the same long-term damage as the average couch potato.• In many cases, Olympian designs serve as the basis for apparel that the average couch potato will be able to buy.• A lot of kids today are overweight couch potatoes.