Anus in a dream: what does it mean?
The body part turns up in dreams far less often than the anxiety about it does, and most reports are about exposure or loss of control rather than about anatomy.
How do the four traditions read it?
Each reading below comes from a named tradition and a cited source, so you can see where it came from and decide what fits your dream. The four often disagree, and that is the point: a symbol rarely means one fixed thing, and the distance between Freud, Jung, modern research and myth tells you more than any single verdict could.
Freud
This is the one place where Freud is unavoidable, since he built a developmental stage around it and tied it to control, withholding and orderliness. Whether any of that survives as science is a separate question from whether it shaped a century of writing, and it did.
After Freud, Three Essays on the Theory of Sexuality (Brill trans., 1910), public domain.Jung
A Jungian reading would be more interested in the shame than in the organ, and would treat the dream as being about what the dreamer thinks is unspeakable rather than about the body at all.
Our summary of a Jungian reading, in our own words, not Jung's. See Jung, ed., Man and His Symbols (1964).Modern
Contemporary dream research does not support the developmental scheme, and treats bodily dreams the way it treats other bodily dreams. As often as not the body is reporting itself: discomfort, illness and needing the toilet all raise the odds of a dream about the relevant part, which is a duller explanation and a better supported one.
Our summary of the neurocognitive account. See Domhoff, The Emergence of Dreaming (2018).Mythological
Older traditions treat the whole area as either comic or polluting and often both at once, with elaborate rules about what may be said aloud. The rules vary enormously and the embarrassment does not.
Rosmerta Publishing editorial synthesis (after Frazer).How can writers use this symbol?
The same symbol, read as craft material rather than as a dream. What it does on the page, how genres use it differently, and what happens when you turn it inside out. Written for novelists, screenwriters and poets who need the symbol to actually work, and it ends with something to try.
In literature
Almost every language has a full comic register here and almost no literary fiction uses it, which leaves a strange hole in the middle of the realist project. Writers who go there tend to be doing something deliberate about dignity.
Rosmerta Publishing editorial synthesis. Our own words; no quoted text.What it does in a story
It is the fastest available way to strip a character of authority, which is why farce reaches for it and tragedy does not.
Genre conventions
Comic writing uses it constantly. Medical realism uses it flatly. Literary fiction mostly declines, and the declining is itself a convention.
How to subvert it
Write it entirely without comedy and entirely without pathos, as a nurse would, and see what is left.
Try this
Write three hundred words of a hospital ward at four in the morning. Keep every word of it plain.
Only the first of these names a source. What a symbol does in a story, how genres treat it, how to invert it and what to try are our editorial judgement as writers and editors, not findings from a body of research. They are offered as craft opinion and should be argued with.