Typewriter
The first-person narrator of the story is a young boy living in the modern world of computer and cell phones. As a result, he is not exactly familiar with typewriters as a part of his daily existence. On a field trip, he discovers that an electric "typewriter is heavier than you would believe...makes a loud buzzing noise...but I like the whack-whack-whack when you type." This imagery conveys not just the weight and sound of a typewriter as opposed to a laptop or tablet, for instance, but is also suggestive of the narrator's affinity for retro style.
Poop
The imagery of poop permeates throughout the book, as might well be expected from the title. Imagery that focuses on this topic is not always disgusting, but sometimes definitely is distasteful. "Well, all food is pre-poop, but burritos are more pre-poop than anything." This particular use of imagery is dependent upon a familiarity with the food in question. More importantly, it is also dependent upon familiarity with burritos that are less than appetizing in appearance. The point being made is that visiting the so-called "poop fountain" is not really as bizarre an endeavor as it might seem. People come into contact with things that resemble the subject in question all the time.
The Smell
Any book for children promising a poop fountain is bound to include imagery focusing on the sense of smell. "It just seemed that it was getting heavier and thicker...like you could reach out and touch it. Afterward, we all agreed that it felt like we could actually feel the stink particles sticking to our clothes." The unusual thing about this use of imagery is that the foul odor of the title material is conveyed not olfactorily but by appealing to the sense of touch. The unpleasantness of the smell is made more tangible through the way it feels to the characters.
Trailer Parking
Some of the characters who populate the story live in a trailer park. When the narrator learns that a girl he likes is on the verge of moving in with her family. When she asks if it is a nice place, he replies "This was obviously not the time to tell her about the guy with the world's loudest car who goes to work at 4:30 in the morning." This is an effective use of imagery to describe specifically one unpleasant feature about this particular trailer park rather than broadly stereotyping trailer park living negatively.
