The sour scent of sweat pierced the night air. The forest floor was barely visible under beach towels covered with Scout patches displayed for trading. A tiny youngster in a baseball cap skipped frenetically through the crowd, his high-pitched scream rising over a cacophony of haggling.

"Anyone want this?" he yelled, holding a patch aloft. He stopped, jabbing his fingers at the patch. "Look! It's silk! SILK!"

Nearby, Tim Baldwin, 16, of West Chester, Pa., tried to pawn off a piece of "bait" -- a truly lame Cub Scout patch covered with rainbows and bears and the words "Day Camp." He fibbed, earnestly telling the trader that it was unique, and scored a patch showing a cartoonish bee. But it was a Boy Scout patch -- a slight step up.

This is the heated world of patch trading at the National Scout Jamboree, one so addictive that some Scouts practically abandon canoeing and mountain biking to concentrate on frenzied quests for patches that glow in the dark, change color when warmed by the sun or feature the video game Halo.

Today, the last day of the quadrennial campout, many of the 32,000 Scouts here will depart with bags full of patches -- the kind meant to be keepsakes, not earned. Most Scouts will have traded fairly, but some will have deceived, stolen and even paid -- a strictly forbidden practice -- for their treasures. Once home, the fever worn off, most will store them until the next Jamboree.

"It's gone overboard," said Tony DiSalvo, 76, a Distinguished Eagle Scout from Williamsport, Pa., who has attended every jamboree since the first one, in 1937. "But they enjoy it, so what are you going to do?"

For 10 days, business has been brisk. Scouts have lined roads all day, their wares displayed in neat rows. Come nightfall, they toted their collections and lanterns out to wild patch bazaars, where they sealed deals with handshakes and called one another "Sir."

"There's no friendly words," said Chuck Schappert, 16, one of Baldwin's troop mates. "It's strictly business."

In the old days, Scouts traded to learn about each other. Iowa troops, for example, would swap patches and homegrown potatoes for a California troop's patch and a chunk of redwood.

Fellowship remains; some Scouts collect patches from each state, and brief chats ensue over most trades. But the targets for the most rabid collectors are "top tier" patches, official 2005 jamboree badges craved for their rarity -- some councils order fewer patches -- or design.

During this jamboree, those included the Connecticut Rivers Council's patches, which are adorned with the green lizard of SoBe beverages, and the Bay Area (Tex.) Council's Halo patch -- for which, rumor has it, one Scout traded his iPod.

"People will trade anything for a Halo patch," said Erik Chumbley, 15, of Colorado Springs.

That is, Scouts say, until word got out that a shipment of Halo patches arrived over the weekend, reducing their value and causing demand for SoBe patches to skyrocket. By Monday, though, the shipment report was in doubt, and Halos were back on top.

Other market forces, such as jamboree geography, are also at work: A Pennsylvania patch is no big deal near the Northeast troops' campsites. Carry it two miles to the Western Region camps and it's like Marco Polo bringing spices to Venice.

Stories of theft abound. Ruthless Scouts stick duct tape to their boot soles and slyly step on desired patches. Traders protect against crime by covering their merchandise with clear plexiglass or, like one Scout, using a mom-made blanket with transparent plastic compartments for display.

Owners of coveted patches demand multiple patches for a trade, which Scout leaders condemn. Scouts determined to make such deals move farther toward the center of the campus, where adults less often tread.

On Friday, Erik and troop mate Thomas Foster, 12, set up shop near a row of portable toilets at the juncture of two jamboree arteries. Chumbley said he caught the trading bug only upon arriving at jamboree, having previously deemed the hobby "extremely dorky, like beyond belief."

On his towel lay his favorite, a jamboree-edition Virginia State Police patch showing a patrol car with battery-operated flashing lights. Erik said it was a "four-for-one" patch.

A bespectacled Scout arrived, his eye on the police patch, a stuffed resealable bag under his arm. He skipped the greeting and offered three patches; Erik declined. The Scout offered two others, one of them a Snoopy patch that Erik desperately wanted. Erik offered other patches, but the kid wanted the police patch and countered with four patches, including the Snoopy.

Erik deliberated. "It is a light-up," he said of his police patch. "But I have always had a thing for Snoopy."

No deal was made.

Hidden in his bag, Thomas had one of the Hooters patches circulating the Jamboree -- illicit badges known as "spoofs" that, officials said, probably were traded by an outsider seeking official jamboree patches, which do good business at Scout memorabilia trade shows and on eBay.

Scouts and leaders say that trading, no matter how cutthroat, offers valuable business lessons. It can teach strategy: Many Scouts pair up, one scoping for patches and one staffing the towel. And marketing: On a recent night, two Scouts decided to place their patches on posters of bikini-clad women.

Some leaders joke that today's Scouts learn such lessons too well. David DeCaires, a scoutmaster from Oahu, Hawaii, cited the rule -- often broken, Scouts say -- prohibiting trades between adults and Scouts.

"In all reality, I think it's to protect the adults from the boys," he said.

Patch trading is so frenzied that some Boy Scouts practically abandon other activities.