Jimmy bombed his own copier job chance on purpose: after impressing the interviewers, he came back in and insulted them, basically telling them they were suckers for hiring him. The scene is often read as Jimmy rejecting a normal, steady path because he felt ashamed and wanted to stay in control instead.

What happened

He interviewed very well and almost certainly would have gotten the job.

Then he sabotaged it by shifting from charming sales mode into open contempt, mocking the people interviewing him.

Why he did it

The moment is usually interpreted as self-sabotage mixed with pride and guilt.

In other words, Jimmy didn’t just turn down a copier job; he rejected the whole idea of being “ordinary” and working for people he could outmaneuver.

In one line

He talked himself out of the copier job by insulting the interviewers after winning them over.

TL;DR: Jimmy was offered the copier job vibe, then torched it himself by calling the employers suckers and walking away on his own terms.