Couch potato (9)
(Other definitions for layabout that I've seen before include "Do-nothing, loafer" , "Lazybones" , "One doing little work" , "Lazy person" , "dosser" .)
(Other definitions for lazybones that I've seen before include "Idle person" , "Idle type" , "Idler (colloq.)" , "He does nothing" , "Slacker" .)