Put your back up

Definitions

become defensive or angry
To describe someone becoming defensive or angry in response to a perceived threat or insult
prepare for a fight or challenge
To describe someone getting ready to face a difficult situation or confrontational person

Examples of Put your back up

The boss's criticism really put John's back up during the staff meeting.

In this example, "put your back up" is used as a phrasal verb to indicate that John became defensive or angry in response to the boss's criticism. It's a figurative idiom that means to become irritated or upset, as if someone's words are pushing them backwards.
The initial price quote for the project put our client's back up, and we had to negotiate over email to come to a mutually agreeable cost.

Here, "put your back up" is used again to refer to the client's negative reaction to the initial price. It can also mean that something has caused someone to resist or oppose an idea or proposal.
I wouldn't want to be on the receiving end of what put my coworker's back up during the presentation yesterday.

This usage shows that "put your back up" can also indicate that someone's behavior or action was the cause of another person's negative reaction. In this example, the speaker is warning someone else that their coworker might be angry or upset about something that happened during a presentation.
The long wait at the DMV really put my patience back up.

In this example, "put your back up" is used less commonly, but still accurately: it's used metaphorically to express the idea that someone's emotions or dispositions have been negatively affected by a particular circumstance or event. In this case, the speaker is saying that the long wait at the DMV (Department of Motor Vehicles) has made them lose patience or become angry.
The sales manager's proposal was met with resistance from some of the employees, causing the manager's back to go up in frustration.

When someone's back goes up, it means they become defensive or angry in response to a perceived threat or criticism. In this example, the sales manager's proposal was not immediately accepted by everyone, which led to the manager becoming defensive and frustrated.
After the boss criticized her work, Sarah's back went up and she stormed out of the room.

In this example, Sarah's boss criticized her work, which caused Sarah to become angry and defensive. As a result, Sarah's back went up and she left the room in a fit of anger.
The disagreement between the two politicians caused sparks to fly and both of their backs to go up.

This example uses the expression "sparks to fly" to describe the intense argument between the two politicians. The argument was so heated that both of the politicians became defensive and angry, causing their backs to go up.
The customer service representative's back went up when the customer demanded a full refund for a product she had already used.

In this example, the customer demanded a full refund for a product that had already been used, which caused the customer service representative to become defensive and angry. As a result, the representative's back went up in response to the customer's request.

Conclusion

The idiom "put your back up" can be used to describe someone becoming defensive or angry, or preparing for a fight or challenge. It is often used in situations where someone feels threatened or provoked and is getting ready to defend themselves.

Origin of "Put your back up"

The origin of the idiom "put your back up" is not entirely clear, but it is thought to come from the behavior of animals when they feel threatened. When a cat or dog feels threatened, they often arch their backs to make themselves appear larger and more intimidating. This defensive posture is similar to the figurative meaning of the idiom, suggesting that someone is getting ready to defend themselves in a confrontational situation. The idiom has been in use for several centuries, and its origins can be traced back to the behavior of animals in the face of danger.