For "someone who makes jokes", see wikt:jokester.

Jokester is a science fiction

Science fiction

Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 short story

Short story

A short story is a work of fiction that is usually written in prose, often in narrative format. This format tends to be more pointed than longer works of fiction, such as novellas and novels. Short story definitions based on length differ somewhat, even among professional writers, in part because...

 by Isaac Asimov

Isaac Asimov

Isaac Asimov was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular science books. Asimov was one of the most prolific writers of all time, having written or edited more than 500 books and an estimated 90,000...

. The story first appeared in the December 1956 issue of Infinity

Infinity (magazine)

Infinity Science Fiction was a short-lived American science fiction magazine. It was published from November 1955 to November 1958 and released a total of 20 issues. The editor of the magazine was Larry T. Shaw...

, and was reprinted in the collections Earth Is Room Enough

Earth Is Room Enough

Earth Is Room Enough is a collection of fifteen short science fiction and fantasy stories and two pieces of comic verse published by Isaac Asimov in 1957. In his autobiography In Joy Still Felt, Asimov wrote, "I was still thinking of the remarks of reviewers such as George O. Smith . . ....

(1957) and Robot Dreams

Robot Dreams

Robot Dreams is a collection of science fiction short stories by Isaac Asimov, illustrated by Ralph McQuarrie. The title story is about Susan Calvin's discovery of a robot with rather disturbing dreams. It was written specifically for this volume and inspired by the McQuarrie cover illustration...

(1986). It is one of a loosely connected series of stories concerning a fictional computer

Computer

A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

 called Multivac

Multivac

Multivac is the name of a fictional supercomputer in many stories by Isaac Asimov. According to his autobiography In Memory Yet Green, Asimov coined the name in imitation of UNIVAC, an early mainframe computer...

.

Plot summary

Noel Meyerhof is a 'Grand Master', one of a small cadre of Earth's recognised Geniuses, who has the insight to know what questions to ask Multivac. But a computer scientist is concerned that Meyerhof is acting erratically. As a known joke-teller, he has been discovered feeding jokes and riddles into Multivac.

By computer analysis, the characters in the story investigate the origin of humor, particularly why there seems to be no such thing as an original joke, except for puns. Every normal joke is something you heard from someone else.

The computer eventually tells them that humor is actually a psychological study tool imposed from without by extraterrestrials studying mankind. They needed to isolate the responses to their jokes from original ones, so they 'programmed' us to react differently to puns.

They also find that figuring this fact out makes it useless as a tool, so the unidentified aliens turn off humour. Nothing is ever funny again.