sad sack

noun2

1. •
   (US) An incompetent or inept person.

   • One law enforcement official played down Mr. Defreitas’s ability to carry out an attack, calling him “a sad sack” and “not a Grade A terrorist.” — 2007
2. •
   (US) A perennial failure or victim of misfortune.

   • “Super Sad” takes as its Romeo and Juliet, its Tristan and Iseult, a middle-aged sad sack named Lenny Abramov and a much younger beauty named Eunice Park. — 2010