Ever wanted to climb an acne wall? Explore the science of flatulence at the "Toot Toot" center? Or try your hand at a round of "Urine: The Game"?

You'll soon get your chance when the Reuben H. Fleet Science Center opens "Grossology: The (Impolite) Science of the Human Body." The traveling exhibition, which opens a three-month stop at the Balboa Park museum on Saturday, uses creative exhibits and animatronics to tell the good, the bad and the downright ugly about runny noses, body odor, burps and other bodily functions.

Designed especially for the grade-school crowd (who seem to find potty humor endlessly amusing), the "Grossology" exhibit was inspired by microbiologist Sylvia Branzei's best-selling children's book "Grossology: The Science of Really Gross Things."

The exhibit has been a smash everywhere it has toured, so Fleet officials are optimistic about the future of "Grossology."

"We've been waiting for this exhibit for more than two years and we're hoping it will be really popular with our guests," said Paul Siboroski, exhibits director at the Fleet. "A lot of people are familiar with (Branzei) and her books and there's a built-in audience who know what she's about."

Although a burp machine and stinky foot box are bound to cause giggles and snorts, Siboroski said there's real science behind the silliness in "Grossology."

"People will be surprised that you can have a serious discussion about science here, but you have to make it appealing to your audience. You can snicker and laugh and joke about it, but you're still learning and exploring," he said.

The target audience for the exhibit is grades four through six, Siboroski said. "That's the age when boys and girls begin to discover their bodies and they ask questions about why things are and the way things are. This exhibit allows them to learn all about their bodies in a fun and interesting way."

Among the 2,500-square-foot exhibit's featured attractions are the Vomit Center, where children can learn about the process of vomiting (and listen to the associated retching sounds). Kids can create a giant belch at the Burp Machine (which creates a build-up of acid in a container with soda pop). They can climb up a large rubberized replica wall of "human skin" where scabs, pimples and blisters serve as toe- and finger-holds. They can explore the role of the kidney by playing the "Urine" video game. They can sniff scent boxes that evoke the smell of foot and body odor, among other unpleasant smells. They can play what looks like a giant board game of "Operation," where they try to remove the organs from a patient on an operating table. Or they can visit Nigel Nose-It-All, a life-sized animatronic character (whose head is a giant faucet) who explains everything there is to know about runny noses.

The exhibit has been a hit virtually every museum it has visited since the tours began six years ago. More than 400,000 people toured "Grossology" during its three-month visit to the Oregon Museum of Science & Industry (100,000 more than the museum's previous record-holding dinosaurs exhibition). And the Chicago Academy of Sciences reported a 150 percent increase in attendance after the exhibit opened in 2001.

To kick things off in San Diego, the Fleet museum is hosting the GrossOlympics from 10 a.m. to 4 p.m. Saturday.

Children ages 6 to 14 are invited to participate in a series of wacky contests, including smelliest sneakers, loudest burp and longest-distance spitting. There will also be a relay event for the fastest team to move a tennis ball through an "intestinal track" tube and other body-themed games. Sign-ups will be taken an hour beforehand and prizes will be awarded. Participation in the games is free with paid museum admission.

Info Box:

"Grossology: The (Impolite) Science of the Human Body"

When: Opens Saturday (Jan. 20) and runs through April 29; museum hours, 9:30 a.m. to 5 p.m. Mondays-Thursdays, 9:30 a.m. to 9 p.m. Fridays, 9:30 to 8 p.m. Saturdays and 9:30 a.m. to 6 p.m. Sundays

Where: Reuben H. Fleet Science Center, 1875 El Prado, Balboa Park, San Diego

Tickets: 11.75, adults; $9.75, seniors and children ages 3 to 12; children 2 and under are free (price includes one IMAX film); exhibit-only admission is $6.25 to $7

Info: (619) 238-1233

Web: www.rhfleet.org