ERICH SEGAL HAS written a sequel to Love Story, his tale of passion at Harvard and Radcliffe. Called Fairy Tale, it reasonably could be expected to deal with homosexuality at Yale, but it doesn't. Instead, it borrows the locale of Deliverance, although it leaves out the sodomy.

Fairy Tale is 47 pages of pictures and prose about hillbillies. Segal tells the story of a hick kid who goes into the big city to buy a used car from a dealer named Happy Humphrey, gets swindled, but through an ironic twist of fate wins out in the end. Happy Humphrey trades Jake Kertuffel a handful of lima beans (from which a money tree is supposed to grow) for the Model T in which the Kertuffel clan has sent its scion into the city. Ironically, a money tree springs up, and the Kertuffels buy a Cadillac with some of their money. Happy Humphrey, in a jealous rage, chops down the tree, but goes to jail for trying to pass the eight dollar bills the tree was producing when he killed it.

ADMITTEDLY IT'S NOT much plot for five dollars, and Segal doesn't make up for that weakness in any other department. He's dispensed with things like descriptive prose, character development or even the maudlin emotion-grabbing of Love Story. Apparently amusement is the goal of this little book, and any strenuous exercise of intellect or emotions beyond that of, say, The Secret Storm or The Edge of Night is too tiring to be amusing.

But in lots of ways this is an uncomfortable book. It isn't a child's Fairy Tale--too much of the humor of the thing is of a mildly sick adult variety, the degenerate offshoot of upper-middle class Broadway comedy, with its pallid neuroses that all the ashamed afflicted can laugh at. Segal also makes a real effort at verbal acrobatics, and falls flat. "Magic beans, the stuff dreams are made of! And also magic vegetable stew," can't qualify as one of the better bits of verbal word play of the late 20th century.

Love Story was a pretty low starting point. But at least it lacked the self-conscious nervousness that runs through this effort. In Fairy Tale, Segal does not even reach the heights attained by Jonathan Livingston Seagull. For some reason, every time he has the opportunity, he takes the cheap shot, makes some inane remark, or collapses into an idiot's snideness.

Five dollars for a 47-page book might appear to be a bit steep. Ten of the pages have absolutely no print on them, and seven have less than a full sentence: The deal is worse than it first appears. There is a brighter side to all of this. Each page of pictures is one less printed page to read. And though Dino Kalupolis's pictures are bad, there is no need to stare at them for any length of time.

All in all, it is very irritating to spend an hour writing a review of a book that it takes 15 minutes to read and that Segal probably spent 45 minutes writing. This is the classical case of a book not worth reading, not worth writing, probably not worth writing about, and maybe not even worth reading about.