sad sack, a
1. noun A hopelessly inept, blundering person who can't do anything right. That poor sad sack Sarah has been stuck in the same dead-end role in this company for years.
2. noun A sad, moping person, especially one who refuses to try and improve their mood or situation. Don't be such a sad sack—I know you're disappointed about missing the concert, but that doesn't mean we can't have fun tonight! He just sat there like a sad sack, sulking in the corner of the party.
3. verb To be in a sad, moping mood, especially while refusing to try and improve one's mood or situation. Usually used in the continuous tense; sometimes hyphenated. If you don't quit sad sacking back there, I'm going to turn the car around and drive us all straight back home! Bill's been sad-sacking around the office ever since he got passed over for the promotion.
A singularly inept person, as in Poor George is a hopeless sad sack. This term alludes to a cartoon character, Sad Sack, invented by George Baker in 1942 and representing a soldier in ill-fitting uniform who failed at whatever he tried to do. It was soon transferred to clumsily inept civilians.
sad sackan inept blundering person. informal, chiefly US
n. a sad person; a listless or depressed person. Tom always looks like such a sad sack.
sad sack, a
A pathetically inept individual. The term comes from a cartoon character named Sad Sack, invented by Sgt. George Baker and very popular during World War II. Baker’s representation of a limp-looking soldier in ill-fitting, loose-hanging uniform, who tried to do his best but was neither smart nor lucky and consequently failed at whatever he undertook, caught on, and the name was transferred to the inept in civilian life.
See also: sad