What about Orwell's double plus ungood? Though I know that's not what he meant. Nobody don't know nuffin, these days.

What is the difference between a 'not impossible she' and a possible she?

Allen has a point - and, John, there is a world of difference!

Talking In Bed

Talking in bed ought to be easiest
Lying together there goes back so far
An emblem of two people being honest.

Yet more and more time passes silently.
Outside the wind's incomplete unrest
builds and disperses clouds about the sky.

And dark towns heap up on the horizon.
None of this cares for us. Nothing shows why
At this unique distance from isolation

It becomes still more difficult to find
Words at once true and kind
Or not untrue and not unkind.

Philip Larkin (my italics, though)

I think this one, from Chaucer, takes the prize. Four negatives:

He never yet no villainy ne said
In all his life unto no manner wight....

Good one, Ann.

How about Ian Dury's Clever Trevor?

just cos I ain’t never ‘ad, no, nothing worth having
never ever, never ever
you ain’t got no call not to think I wouldn’t fall
into thinking that I ain’t too clever
and it ain’t not having one thing nor not another
niether, either is it anything, whatever
and it’s not not knowing that there ain’t nothing showing
and I answer to the name of Trevor, however

Just cos I ain’t never said, no, nothing worth saying
never ever, never ever, never ever
things ‘ave got read into what I never said, ‘till me mouth becomes me ‘ead
which ain’t not all that clever
and it’s not not saying one thing nor not another
neither, either is it anything I haven’t said, whatever
and it ain’t not proving that me mind ain’t moving
and I answer to the name of Trevor, however

knock me down with a feather
Clever Trevor
widebrows wonder whether Clever Trevor’s clever
either have they got
nor neither haven’t not
got no right to make a clot
our of Trevor

why should I feel bad about something I ain’t ‘ad
such stupidness is mad cos nothing underfoot
comes to nothing less to add to a load of old toot
and I ain’t half not half glad cos there’s nowhere to put it
even if I ‘ad i’m a bit of a Jack the Lad

knock me down with a feather
Clever Trevor
widebrows wonder whether Clever Trevor’s clever
either have they got
nor neither haven’t not
got no right to make a clot
our of Trevor

also, it takes much longer to get up north, the slow way

Thanks for posting this one, Philip. What a master Dury was at this sort of thing.

I had no idea people would take this and run with it to this extent.

Of course my favorite example is the classic poem from Enoch Soames' volume "Fungoids":

TO A YOUNG WOMAN

Thou art, who hast not been!
Pale tunes irresolute
And traceries of old sounds
Blown from a rotted flut
Mingle with noise of cymbals rouged with rust,
Nor not strange forms and epicene
Lie bleeding in the dust,
Being wounded with wounds.
For this it is
That is thy counterpart
Of age-long mockeries
Thou hast not been nor art!

There's a typo in L4, Gail - 'flut(e)'

Max comments: As for the craftsmanship, "rouged with rust" seemed to me a fine stroke, and "nor not" instead of "and" had a curious felicity.

Nice going, Holly. I wondered how many of us knew Enoch before
his unfortunate encounter with the devil.