Welcome to English in a Minute! 

This is a chip. Delicious. But why would someone have a chip on their shoulder?

A: Dan, do you have any idea why Craig is mad at me?  
D: He’s just got a chip on his shoulder. It still bothers him that you got that promotion instead of him.  
A: That was months ago! He needs to get over it.  
D: I agree.  

If someone has a “chip on their shoulder,” they feel angry about a past situation. They hold onto the belief that they were treated unfairly. This makes them generally unpleasant to be around.  

And that’s English in a Minute!