Wiktionary
n. A sheath, usually of plastic, designed to fit in a shirt pocket and hold pens and other small implements, preventing them from tearing or staining the shirt.
Wikipedia
A pocket protector is a sheath designed to hold writing instruments and other small implements, such as slide rules, while preventing them from damaging the wearer's shirt pocket (e.g., by tearing or staining by a leaky pen). The pocket protector is designed to fit neatly inside the breast pocket of a shirt, and may accommodate pens, pencils, screwdrivers, small slide rules, and various other small items. A flap overlapping the pocket exterior helps to secure the pocket protector in place.
The pocket protector was invented during World War II by Hurley Smith while he was working in Buffalo, New York. He was awarded for the device on March 18, 1947; the patent was filed on June 3, 1943.
A competing claim for the invention came from Long Island plastics magnate Gerson Strassberg around 1952. Strassberg was working on plastic sleeves for bankbooks. One day he placed one that he was working on into his shirt pocket while he took a phone call. When he noticed it there, he realized it would make a great product.
Originally fashioned from polyvinyl chloride (PVC), pocket protectors were first marketed toward corporations as branded promotional fare. However, a more general market for the product soon arose, made up of students, engineers (prominently mechanical), and white-collar workers in sundry fields. The accessory has become part of a " nerd" or " geek" fashion stereotype, probably because of its association with engineers or students.
Usage examples of "pocket protector".
Rothman fumbled at his breast pocket - he was in the remains of slacks and shirt with pocket protector - and brought out a pair of glasses.
One of the pens in his plastic pocket protector rammed into her cheek.
He pulled what looked to be a thick pen out of the pocket protector and unscrewed the cap.
To her absolute amazement, she noticed a plastic pocket protector in the shirt pocket.
In his plastic pocket protector were three pens, a tiny calculator and a sales tax chart.
He had thick glasses and pudgy fingers, and would have looked more at home with a pocket protector than with the spiked leather gloves on his fingers.
She thought the only thing he lacked was a plastic pocket protector and several pens to make the picture complete.
Kris could never remember seeing him without his pocket protector and the dozens of pens and pencils that rested there along with his calculator.
There was enough explosive force in that backpack to bring down half the building, and it had been packed into a plastic sheet that looked like a laminated pocket protector.
His pants were polyester and his shirts white, and he wore a pocket protector with no sense of irony.