I read the story maybe 30 years ago but it may be older. A guy is living backwards, maybe as a result of some scientist doing something to him. The part I remember is him getting food by going into a grocery store and walking backward so that to observers living forward it looked like he was putting stuff on the shelves. Weird behavior, sure, but not something that anybody would freak out over.
"The Chronokinesis of Jonathan Hull", a short story by Anthony Boucher in his Fergus O'Breen series; first published in Astounding Science Fiction, June 1946, available at the Internet Archive; reprinted a few times.
A guy is living backwards, maybe as a result of some scientist doing something to him.
Two guys, actually; the Mad Scientist who built the time machine, and his assistant:
Givens did not notice my concern, but casually asked, "O.K. yet, M. S.?" He thought it humorous to call me "M. S.," which was, indeed, one of my degrees but which he insisted stood for Mad Scientist.
Whatever was wrong I would not find it out by staying there. Perhaps nothing whatsoever had happened. And yet that curious wrenching sensation surely indicated that the temporomagnetic field had had some effect.
I beckoned to Givens to follow me, and we stepped out of the machine. Two men were backing away from it in the distance. Their presence and their crablike retrograde motion worried me, and reminded me of those other two whom we had only glimpsed. To avoid them, we hastily slipped out the rear door, and into a world gone mad.
For a moment I had the absurd notion that some inconceivable error had catapulted us into the far distant future. Surely nothing else could account for a world in which men walked rapidly backwards along sidewalks and conversed in an unheard of gibberish.
But the buildings were those of 1971. The sleek atomic motorcars, despite their fantastic reverse motion, were the familiar 1972 models. I realized the enormity of our plight just as Tim Givens ejaculated, "M. S., everything's going backwards."
"Not everything," I said succinctly, and added none too grammatically, "Just us."
The part I remember is him getting food by going into a grocery store and walking backward so that to observers living forward it looked like he was putting stuff on the shelves. Weird behavior, sure, but not something that anybody would freak out over.
We had by now learned to walk backwards, so that we could move along the streets without exciting too much comment. Visualize this, and you will see that a man walking backwards from 12:00 to 11:55 looks like a man walking forwards from 11:55 to 12:00.
Visualize it further. A man moving in this wise who enters a store empty-handed at 12:00 and leaves loaded with food at 11:50 looks like a normal man who comes in with a full shopping bag at 11:50 and leaves without it at 12:00—a peculiar procedure, but not one to raise a cry of "Stop thief!"
Is it possibly The Curious Case of Benjamin Button?
On the evening of November 11, 1918, a boy is born with the appearance and maladies of an elderly man. After the baby's mother, Caroline, dies during childbirth, the father, Thomas Button, abandons the infant on the porch of a nursing home. Queenie and Mr. "Tizzy" Weathers find the baby, and Queenie decides to raise him as her own, naming him Benjamin.
In 1947, Benjamin visits Daisy in New York unannounced, but departs upon seeing that she has fallen in love with someone else. In 1954, Daisy's dancing career ends when her leg is crushed in an automobile accident in Paris. When Benjamin visits her, Daisy is amazed by his youthful appearance, but, frustrated by her injuries, she tells him to stay out of her life.
In 1990, widowed Daisy is contacted by social workers who have found Benjamin — now physically a pre-teen. When she arrives, they explain that he was living in a condemned building and was taken to the hospital in poor physical condition, and that they found her name in his diary. The social workers say he is displaying early signs of dementia. Daisy moves into the nursing home in 1997 and cares for Benjamin for the rest of his life.
In Spring 2003, Benjamin dies in Daisy's arms, physically an infant but chronologically 84 years of age. Having finally revealed the story of Caroline's father to her, Daisy dies as Hurricane Katrina approaches.