So is this primarily the role of a male?
Yes, it is.
Does the role pertain to the general field of religion?
Not at all.
What about the field of entertainment, including sports?
Good guess, but not even close.
What about the realm of politics, including the military?
Nope. Not an occupation.
Is this some fictional character or member of a group of such “people”?
And another no, sorry. It’s a real life role.
Cops?
No, not an occupation.
Does the role we are not to mention often appear in sketches and parodies in places like SNL or National Lampoon?
Could it be something like, “You never can expect the Spanish Inquisition.”
It could, but it’s actually very common and day-to-day.
Though not quite day-to-day (or even common) there was a local area commercial many years ago promoting a local dairy (if I remember right). The punchline in at least 20 iterations of the basic theme was “Don’t pay no 'tention to kangaroos.” As I recall it was along the lines of the little character in the Hawaiian Punch things that was always punching some other character.
Anything like that that we’re trying to identify?
No, here’s a clue: think along the lines of friends and family.
Here’s a sample of those thought:
Don’t mention the black sheep of the family.
Who is the red-headed stepchild?
Who’s yo’ daddy?
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Would the typical American 21st Century family have at least one of these unmentionable types as members?
Have we established that the unmentionable is a male? If so, would he be under the age of 40?
Male, possibly under 40, but not necessarily. The samplings are much, much closer, but these don’t violate the exact rule.
I didn’t see your answer to
Is the unmentionable aspect due to some illegal behavior?
Nobody talks about Uncle Joey’s transgressions.