The Rooter-Tooter - handy for heckling referees - and a mug that melts as you drink from it are two of the weird and wacky gadgets inventors hope will become the latest fads.

More than 30 inventors from around the country converged on the "Fad Fair" at the Franklin Institute Science Museum on Friday. There they showed off such goofy gizmos as decorative noses, balls made of "ooze" and bicycle helmets with three-dimensional funny faces.The fair, which runs through Sunday, was organized by Ken Hakuta, better known as "Dr. Fad" to viewers of a local children's television show.

Hakuta is also the inventor of the Wacky Wallwalker. Throw the sticky, octopus-like toy against a wall and it crawls down by itself. It has helped Hakuta walk off with more than $20 million over the past eight years, he says.

Most of the inventions on display need backers. Hakuta predicted 10 of those would be marketed and two would make money. That doesn't discourage the inventors.

"These are the eternal optimists," he said.

Martha C. Crossley is hoping her "Narly Noggins Helmet Stuff" will be a hit with kids who don't like to wear bicycle helmets.

She was on a camping trip in New Hampshire when the talk turned to trying to get kids to wear bicycle helmets. The helmets were too plain, she and her friends reasoned, but liven them up with three-dimensional monster features and they might be a hit.

The helmet add-ons, including goofy eyeballs and demon wings, have just arrived at toy stores, selling for $2.99 to $4.99 a set, says Mrs. Crossley, of Woonsocket, R.I.

Boinks - small tubes of springy plastic in "rad" colors such as neon pink and lime green - already have captured kids' imaginations, says the woman who markets them, Joyce Murphy.

More than 10 million Boinks have sold since Mrs. Murphy's daughter, Colleen, invented them four years ago, she said.

Craig Boyko of Fairfield, Iowa, came to the Fad Fair with two idiosyncratic inventions.

One is the Ooz Ball, made of a substance that stretches, bounces and makes popping sounds. The other is the Bite Lite, a tiny, furry creature with teeth that can grasp a child's clothing and light the way with a flashlight it carries in its tail. Great for kids who are afraid of the dark.

Boyko's first invention was the Zube Tube, a 3-foot cylinder that makes weird noises when people yell through it. About 1 million have sold since 1989.