They have been called many things: go-aheads, zories, thongs, flip-flops, flaps, beach walkers and, in Hawaii, slippers.

That's a lot of names for a simple rubber sandal that was forever falling apart or suffering "blowouts," when the strap pops out at the beach.

Like bikinis and Hawaiian shirts, flip-flops have become a summertime classic. One can still find a basic rubber thong for under a buck at most drugstores.

Over the years, the thong has evolved from the crude Cro-Magnon flip-flop of the past to the sophisticated, virtually indestructible beach sandal of today. The new thongs borrow the high-tech features of athletic shoes and often cost as much. Still, even many souped-up sport sandals have stayed true to the basic three-point design and rubber sole of the early thongs.

The flip-flop was a hit almost from the day it landed on the sandy beaches of Southern California. To be sure, the definitive history of the flip-flop has yet to be written, but surf historian Allan Seymour, 52, of Capistrano Beach, has pieced together a likely scenario of thongs' origins.

Flip-flops originated in Asia as rubberized descendants of the wooden slippers worn for centuries, Seymour says. They were imported to the United States during World War II, when soldiers began wearing them in Hawaii.

"They needed rubber sandals for people to wear when walking around in the submarines," Seymour says.

The Korean War also saw an influx of flip-flops.

"I grew up in Laguna Beach, and I first saw guys coming back from the Korean War wearing these really cheap sandals," he says.

The rubber sandals adapted easily to the laid-back California beach lifestyle and became an instant hit with beach-goers. Seymour recalls seeing bins of thongs selling for 29 cents a pair in front of liquor stores and markets in Laguna during the 1950s.

"We called them go-aheads, because you can't walk backward in them," he says.

Unreliability is part of the flip-flops' lore.

"There was nothing like running down the street and having one blow out on you," Seymour says. "At low tide in Laguna, you'd walk the beach and find flip-flops with one side blown out. If you got a month [of wear] out of them it was a major deal."

No one really minded that the sandals didn't last, because they cost only pennies.

"I blew out my flip-flop. Stepped on a pop top," sings Jimmy Buffett in "Margaritaville," immortalizing the flip-flop's dismal track record.