[Supperman]

When I am an old woman, I shall wear purple
with a red hat that doesn't go, and doesn't suit me.

When I'm an old woman, I shall behave strangely, like wearing purple clothes, red hat, which doesn't fit me. Because I might have dementia.
Here "purple" is the color of noble person, or loyal person, yet, an ordinary people keep away from it because it is weird.

And I shall spend my pension on brandy and summer gloves
and satin candles, and say we've no money for butter.
And I shall spend the whole my pension with luxurious things which should not be needed, and I shall be out of the necessary things.


I shall sit down on the pavement when I am tired
and gobble up samples in shops and press alarm bells
and run my stick along the public railings
and make up for the sobriety of my youth.
I shall ruin my good reputation when I am young, by the strange behaviors such as sitting on the pavement, gobbling up sample foods in shops, and pressing alarm bells.I don't know "run my stick along the public railings" part.I imagine that her stick is J-letter-type and she hang the curved portion of the stick and run along the public railing like a child play of rope-way.Am I correct?

I shall go out in my slippers in the rain
and pick the flowers in other people's gardens
and learn to spit.
All three behaviors are bad manners or even illegal.

You can wear terrible shirts and grow more fat
and eat three pounds of sausages at a go
or only bread and pickles for a week
and hoard pens and pencils and beer nuts and things in boxes.
Here the writer use "you" instead of "I", but it means "I"I shall wear terrible shirts, become more fatty, eat an extraordinary amount of sausages for a challenge, or eat little food for a week.And I shall collect pens and pencils and beer nuts and things in boxes like a child or like a bird/squirrel. The strange behavior which would be done by dementia patients.


But now we must have clothes that keep us dry
and pay our rent and not swear in the street
and set a good example for the children.
I don't know what "clothes that keep us dry" means."pay our rent and not swear in the street " might mean that "We should pay our room-rental fee and we should not declare that we'll do a homeless-life.


We must have friends to dinner and read the papers.
Decent people usually call their friends to their dinner, and read newspapers.

But maybe I ought to practice a little now?
Practice of dementia-life.
So people who know me are not too shocked and surprised
When suddenly I am old, and start to wear purple.
She will give her people the preliminary training of her becoming dementia.

Am I correct, in understanding this poem?