The 'confidence of strangers' is a phenomenon whereby we confide our deepest, darkest secrets in strangers, rather than those known to us - because we don't simply not anticipate ever seeing them again, but actively anticipate never seeing them again, we feel safe in doing so: we need have no fear of their opinion or, more importantly, of their divulging our secrets to others who know us (with potentially negative consequences for us).

There are some things we might divulge to a therapist.

There are others we should probably reserve for strangers.

And then there's ... ... this.

Some things are too perverse even for strangers and we should keep them locked away in our subconscious.