Like many of his delusional daydreams, Walter Mitty’s courtroom dream was triggered by a specific series of events in combination. Driving his car above the speed limit set by his wife triggers his Naval pilot dream. After his wife’s condemnation of his driving and insistence that he see a doctor because he is “tensed up again,” Mitty’s daydream of being a fabulous surgeon begins (one in which he outperforms his actual doctor). A parking lot attendant yelling for Mitty to back his car from the exit lane, which he had pulled into inadvertently while performing fantasy surgery, interrupts this dream. Mitty grumbles to himself about the cockiness of mechanics and garage attendants and tells himself that he will wear a sling next time he uses their services so that they will believe him to be injured and hopefully won’t laugh at him or think him incapable of simple automotive repairs. Once he has purchased the overshoes that his wife insists he should wear, Mitty’s anxiety grows as he tries to remember the other item that his wife had tasked him with getting. The noises of the street combined with his own rumination trigger his courtroom dream after he hears the newsboy “shouting something about the Waterbury trial.” The majority of his daydreams generally lead to his embarrassment at the hands of other, more confident people, but this daydream is actually helpful to Mitty. His imagined final barb at the District Attorney, “You miserable cur!” awakens him from the courtroom daydream into the real world with the phrase “Puppy biscuit,” which turns out to be the item that his wife had put on his shopping list, and the item which Mitty could not remember. A cur is defined as a mongrel, an unfriendly dog; it can also mean a mean, cowardly person.
Mitty’s daydreams are triggered by a combination of his real world environment, his memories, his boredom, and his wife’s control over his life. The daydreams themselves are also combinations of events and images. The gloves his wife insists he wear show up in his surgical dream; the sling that he imagines wearing to the mechanic shop reappears in the courtroom daydream; the pistol presented as evidence in the courtroom daydream returns in his bomber pilot daydream. Walter Mitty is a complex amalgam of clichés, inadequacies, and self-loathing hopelessly trying to daydream himself into the modern world as an accomplished “masculine” man without actually encountering anything of significance within it.
"A newsboy went by shouting something about the Waterbury trial" is what triggers Walter Mitty's daydream. Always forgetting things and being belittled by his wife for this forgetfulness, Mitty fantasizes that he is "the greatest pistol shot in the world" on trial as he suddenly remembers the puppy biscuits.