This is not funny. Not funny at all.

Bill Watterson, creator of the hit comic strip "Calvin and Hobbes," has decided to take a nine-month sabbatical beginning May 5. To millions of daily newspaper readers, it means no new adventures of the rambunctious 6-year-old ("Call me Calvin the Bold") and his ever faithful (and stuffed to everyone but Calvin) pet tiger Hobbes until Feb. 1, 1992."Had I imagined `Calvin and Hobbes' would last this long, I would have paced myself," Watterson says. "The strip requires a great deal of research, and I need to do more interplanetary and paleontology work before I continue."

The decision by the reclusive cartoonist (is there any other kind?) to take some time off raises at least one semi-serious question: Can daily cartooning - coming up with clever gags, drawing little figures, those word balloons - really be that rough?

After all, such celebrated cartoonists as Garry Trudeau ("Doonesbury"), Gary Larson ("The Far Side") and Berke Breathed ("Bloom County") have backed away from the drawing board.

"Oh yeah, it can be hell," says Matt Groening, mastermind behind the popular cult strip "Life in Hell" and television's "The Simpsons." "I've considered (taking a break) myself. But I made a vow when I first started that no matter what happened, I wouldn't give up doing the strip."

"Life in Hell," which Groening distributes through his own syndicate, appears weekly in about 250 publications. He usually produces "Life in Hell" strips two to three weeks in advance (most syndicates require four to eight weeks in advance).

"I'm very sympathetic to what Bill must be going through," Groening said by phone from Los Angeles. "When you put your whole heart and soul into your work, as he, Trudeau, Larson and others do, it can be very demanding and stressful."

Since "Calvin and Hobbes" premiered five years ago, Watterson has produced more than 1,800 strips. The comic strip - No. 1 in most reader and critic polls - appears in 1,800 newspapers. During its hiatus, reprints of earlier strips (many done before widespread syndication) will appear.

This certainly isn't a first in funny-page history.

In 1983, Trudeau broke precedent in the cartooning business by taking a 21-month sabbatical. In 1988, Larson took a 14-month break from "The Far Side" after diagnosing himself a "genuine burnout case." Now, he does five rather than seven panels per week (the others are reprints). Two years ago, Breathed decided to "retire" his Pulitzer Prize-winning "Bloom County," turning his attention to the Sunday-only feature "Outland."

"I'm 32," Breathed said in a 1989 Time magazine interview. "That's too young to coast. I could draw `Bloom County' with my nose and pay my cleaning lady to write it, and I'd bet I wouldn't lose 10 percent of my papers over the next 20 years. Such is the nature of comic strips."

It is estimated that more than 100 million Americans read newspaper comic strips daily. And nothing seems to irritate them more than fiddling with the funnies.

When The Washington Post recently revamped its comic pages to appeal to younger readers - dropping such mainstays as "Gasoline Alley," "Steve Roper & Mike Nomad" and "Mark Trail" (which was later brought back) - the paper received more than 15,000 calls from readers (many angry) and 2,000 letters during a three-week period.

It is estimated that a very popular strip such as "Peanuts" or "Calvin and Hobbes" (appearing in, say, 2,000 papers) could earn a cartoonist as much as $1 million a year from newspaper syndicate fees alone.

A sabbatical "is not something we encourage, and not something we're particularly excited about," confesses Lee Salem, editorial director at Universal Press Syndicate, which distributes "Doonesbury," "The Far Side" and "Calvin and Hobbes." "But we try to understand. Actually, I've accused Garry (Trudeau) of creating a virus in our shop."

Cartoonist or construction worker, most studies have found that workers who take time off come back rejuvenated and more productive.

"Sabbaticals are no longer reserved for academics," says Robert Grandford Wright, a Fulbright scholar and professor of organizational behavior at Pepperdine University in Malibu, Calif. "If we're not careful in our work, we run the risk of losing our passion for it."

The flip side, according to Universal's Salem, is the fear "that newspaper editors won't be so understanding and the readers won't accept the cartoon when it returns."

So far, that hasn't happened.

"Doonesbury" (appearing in about 1,400 dailies) and "The Far Side" (about 1,500) are still hot. Usually, a strip must appear in about 60 papers to be profitable enough to distribute, syndicators say. In most cases, it's the unbridled success of a strip thatallows a cartoonist to call his or her own shots, and sabbaticals.

"You have to remember, the guys we're talking about are very successful," says Judith O'Sullivan, president and chief executive officer of New York's Museums at Stony Brook and author of "The Great American Comic Strip: One Hundred Years of Cartoon Art." "They're like victims of their own success."

O'Sullivan believes the new generation of cartoonists - mainly baby boomers - have the luxury of being able to focus on artistic freedom and expression as opposed to keeping their jobs and making a buck.

The word in comic circles is that Watterson - a shy native of northern Ohio who doesn't grant interviews and hates having his picture taken - devotes a lot of time and research to his strip. He also feels that merchandising - such as stuffed Hobbeses in toy stores - would somehow diminish the strip's overall purity and appeal.

Johnny Hart, the 60-year-old cartoonist who has been doing "B.C." since 1958, says the artists of his generation - including Al Capp ("Lil' Abner") and Mort Walker ("Beetle Bailey") - never really thought about taking time away from work.

"I think we just never had the sense to ask," he said.

Walker, 68, the brains behind "Beetle Bailey" and co-creator of "Hi and Lois," says that even when cartoonists take time off, they usually do weeks of strips in advance. (On average, a cartoonist can spend two to eight hours working on one strip.)

"The most time I've taken away from my strips is about two weeks," says Walker, who has been cartooning for more than 40 years. "But that's OK by me. What we do is a lot of fun."

Most established cartoonists have assistants who help with their strips. And here's one for the funny-paper file: Hart says that sometimes strips run with the same drawings, same word balloons, just different gags and phrases. (Only your cartoonist knows for sure.)

"When you have to produce something fresh, new and funny every single day, seven days a week, 365 days a year, it can be grueling," Hart says. "Do you ever actually get away from this? Not really.

"Sometimes, after I've spent the day playing golf, all I have to do is check the scorecard," he says with a laugh. "Usually, I'll have scribbled all over it. I'll say to myself, `Hey, what's this drawing of a cave man doing next to my score on the par 5?"'