chip on shoulder

a chip on (one's) shoulder

An attitude that leads one to become combative or easily angered. Fred has such a chip on his shoulder—you never know what's going to set him off next. She won't admit it, but Kate has a chip on her shoulder when it comes to discussing her career.
See also: chip, on, shoulder
Farlex Dictionary of Idioms.

*chip on one's shoulder

Fig. a bad attitude that tends to get someone easily upset. (*Typically: get ~; have ~; give one ~.) Why did you get so angry at the slightest criticism? You seem to have a chip on your shoulder.
See also: chip, on, shoulder
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

chip on (one's) shoulder

A habitually hostile or combative attitude.
See also: chip, on, shoulder
American Heritage® Dictionary of the English Language, Fifth Edition.

chip on one's shoulder, to have a

To be quarrelsome; to carry a grievance. This turn of phrase originated in nineteenth-century America, when, according to an article in Harper’s magazine (1857), placing a chip on a man’s shoulder and daring someone to knock it off was a provocation to fight.
See also: chip, have, on
The Dictionary of Clichés by Christine Ammer
See also:
  • chip on one's shoulder
  • a chip on (one's) shoulder
  • a chip on your shoulder
  • have a chip on (one's) shoulder
  • have a chip on your shoulder
  • have a quick temper
  • quick temper
  • short temper
  • be on/have a short fuse
  • have a short fuse