In Chapter 3, Heller constructs a quite unusual sex scene, using a series of similes and imagery. This scene, first described here, will come back up throughout the novel:
Each time she landed with the heel of her shoe, Orr giggled louder, infuriating her still further so that she flew up still higher into the air for another shot at his noodle, her wondrously full breasts soaring all over the place like billowing pennants in a strong wind and her buttocks and strong thighs shim-sham-shimmying this way and that like some horrifying bonanza.
The similes ("like billowing pennants in a strong wind" and "like some horrifying bonanza") have multiple effects on this sentence. For one, this is a long and complex sentence, and the familiar structure of the simile helps to hold the sentence together. The similes are clearer than if Heller attempted to describe the scene more directly.
The similes also work off of each other. The "billowing pennants" describe what the "horrifying bonanza" looks like and vice versa. The similes, together, characterize this sex scene as a disturbingly loud and garish carnival, combining together for a fuller and more evocative image. Thus, together, the similes describe this woman in an unpredictable and strange way.
The rest of the imagery, outside of the similes, elaborates the scene. It is inherently silly: Orr's penis is called his "noodle" and the woman is "shim-sham-shimmying." But it is also fundamentally erotic, in the misogynistic method of this book: the woman is never named but her breasts, buttocks, and thighs are described in detail.
Heller intentionally subverts any attractive or intimate sex scene here. The comparisons to bright flags and a "bonanza," in the similes, emphasize the fact that this is an eminently visible, odd, and uncontrolled situation.
Heller describes Orr's face in rich visual imagery in Chapter 22:
He had a raw bulgy face, with hazel eyes squeezing from their sockets like matching brown halves of marbles and thick, wavy particolored hair sloping up to a peak on the top of his head like a pomaded pup tent.
This is only one long sentence, but it is full of complex images. His eyes look like marbles sliced in half, which is an object that most people likely haven't seen and would have to imagine. "Particolored" means, perhaps obviously, in multiple colors, but it is not a common word, and for that matter hair is usually not particolored naturally. And a "pup tent" is not immediately recognizable to most people who haven't fought in a war: it is a small tent with two triangular openings on either end and two flat diagonal sides. And the tent is "pomaded"; "pomade" is not often used as a verb, and the sense gets more complex when "pomaded" is applied, within the simile, to a tent, not to hair.
In sum, the imagery, and the sentence in which it is presented, is difficult. The reader has to do a little work, or a little guessing, to understand what Orr looks like. This is typical of Heller's imagery: it is specific and intense, but strange and difficult to parse. These images slow the reader down and force them to investigate each aspect of the image. This brings a sense of abstraction to the moment: the reader has to think about the relation of these figurative devices to the real thing. The reader is left to question how "real" Orr is, made up of these absurd images. Heller more often deals with a different type of abstraction, trying to make the war seem absurd through his characteristic paradoxes and contradictions. But in addition to that method, he describes his characters in odd ways that force the reader to slow down, which also creates a sense of absurdity and abstraction.