He's built like a toddler, dumb as a post. By day, he doubles as Mr. Krupp, Jerome Horwitz Elementary's semi-evil principal and the nemesis of the book's true heroes, champion cutups George Beard and Harold Hutchins, who suffer from IBSS (Incredibly Boring School Syndrome).

This is the work of Dav Pilkey, author of the new series Ricky Ricotta's Giant Robot, and illustrator of the Dumb Bunnies books. Captain Underpants books contain several words that are not used in polite society (if such a thing exists anywhere) but cause children, especially boys ages 7 to 10, and even sometimes their parents (particularly after a long day and a glass of wine or two), to double over in laughter.

Try repeatedly saying "Professor Pippy P. Poopypants," the villain of the latest installment - Captain Underpants and the Perilous Plot of Professor Poopypants - and see what happens. Teachers are less pleased when Captain Underpants books make an appearance at show-and-tell.

With four titles and six million Captain Underpants books in print, Pilkey is proof that recovering class clowns can profit from puerile behavior. Captain Underpants is published by those brilliant, now giddy, folks at Scholastic, home to Harry Potter and Pokemon.

The series' other villains include talking toilets and the incredible naughty cafeteria ladies from outer space (and the equally evil lunchroom zombie nerds). Coming next year: Captain Underpants and the Wrath of the Wicked Wedgie Woman. (Watch your back!)

Born in Cleveland, Pilkey, 34, went to Kent State University and now lives on an island in Puget Sound near Seattle. He has a steady girlfriend, no children, and no plans for them. Pilkey, who has a Web site (www.pilkey.com), prefers to do interviews by e-mail. So we did.

	Dav, where's the "e"?
	I lost it when I was a waiter at Pizza Hut back in 1983. They were making a name tag for me, but the letter "e" on the label-maker was broken. Instead of printing "Dave" it printed "Dav." The name stuck.
	Who is Jerome Horwitz and is he pleased you named the school after him?
	Jerome Horwitz was the given name of my personal hero, Curly, from the Three Stooges.
	Who is the model for Mr. Krupp and is he aware of this?
	Mr. Krupp was modeled after two principals and one teacher I had growing up. I'm not sure if they're aware of this or not. I try to stay away from people like that now that I have a choice.
	Do you see each of your series - the Dumb Bunnies, Capt. Underpants, and now Ricky Ricotta - as targeted to different audiences?
	Yes. Ricky Ricotta is definitely for younger audiences. I'd say ages 3 to 8. The Dumb Bunnies and Captain Underpants are for older kids, 5 and up.
	Underpants are a strong leitmotif in your oeuvre. Explain.
	Hang on a second while I get my dictionary.
	What is the highest compliment a reader has given you?
	I hear from parents of reluctant readers who tell me that their kids hate to read but they love Captain Underpants. These kids actually beg for Captain Underpants books. That's pretty cool.
	Who do you see as your average reader?
	I don't have average readers. All my readers are way, way, way above average!
	Why do boys find underwear so funny? Your readership skews 70 percent boys. Do you have any ideas why boys are more attracted to this kind of humor than girls?
	I think underwear is funny because you're not supposed to laugh at it. I'm not sure why boys seem to like this kind of humor more than girls... I get lots of fan mail from girls.
	You were the class clown and the teachers didn't like it, but did you enjoy any aspect of school?
	No.
	When you created the comic Captain Underpants in the second grade, what kind of reaction did you get?
	My friends couldn't get enough of my comics. I was the most popular author in my class. My teachers didn't enjoy my comics, though, and ripped them up whenever they got their hands on them. My parents liked the fact that I was being creative and drawing comic books, but they didn't like the "potty humor." So they encouraged me to make comics about another superhero I had invented called Water Man. Water Man wasn't as silly as Captain Underpants, but I still had fun making up stories about him.
	Would this stuff have been published 20 years ago? Even 10?
	I think so. These books really aren't as naughty as everybody thinks. They're now being translated into Hebrew, for heaven's sake. That's the most sacred language there is, right? So the books can't be that bad.
	What's your response to criticism of your books and others?
	I usually stick out my tongue and make rude noises.
	Do you see your books' success in some way as a response against political correctness?
	No, not really. These books are successful because kids are funny and smart, and the books are funny and smart. It's a perfect match.
	Do you think children's books need to do anything other than entertain?
	I think children's books should always be entertaining. Even the educational ones. But is it enough to just entertain? Sure.
	Are you astonished that you're making a fine living doing this?
	Yeah. I used to get in trouble for being the class clown and now it's my job!
	Was there a backup plan, and if so, what was it?
	I think I could still get my old job back at the gas station if this writing thing doesn't pan out.
	Is there a movie or Saturday morning cartoon deal? If so, who do you see playing Cap't U?
	Lots of offers, but no bites. I had always hoped that Chris Farley would play Captain Underpants, but that didn't work out. I really can't see anybody else in that role, so if there ever is a movie or TV show, it will have to be animated.
	Do you see yourself drawing a rotund bald guy in cape and underpants when you're 90?
	I sure hope so.