mouse potato 
noun informal
A person who spends large amounts of leisure or working time operating a computer.Nobody allows you to remain a couch potato or a mouse potato any more: you have to respond to polls, contests, and invitations to what is being said on the programme on air....
- Her lack of wireless is really holding her back from becoming a full fledged mouse potato.
- PC nerds addicted to their computers will be known as ‘mouse potatoes’, even if they are e-mailing their ‘keypals’, the new word for penpals.
Origin
1990s: on the pattern of couch potato.