|slang (US) an inept person who makes mistakes despite good intentions|
|[C20: from a cartoon character created by G. Baker, US cartoonist]|
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.