(FORTUNE Magazine) – Hurrying through the airport, you feel a tap on your shoulder, and a concerned young lady tells you a streak of ketchup has somehow landed on your back. What the...? Damn. She offers a Kleenex. You put down your fully loaded, 100-gigabyte laptop with the secret plans for Really New Coke, doff your jacket, and madly dab. Seconds later, you turn to go--but your computer's already gone! You just fell for the condiment caper.

In this updated version of an old con--call it Grand Theft 2.0 --portable computers have replaced suitcases as targets for rip-off artists, says Kevin Coffey, a Los Angeles police detective sergeant specializing in airport theft. "They use small condiment packages to squirt the stuff on your back. While one is helping you get it off, suspect two comes from behind and grabs your computer."

Another ruse: The flustered gent in front of you triggers the metal detector, then holds up the line by spilling his change. Meanwhile his well-dressed accomplice is probably lifting the laptop you've already sent through the X-ray machine.

Harried business travelers at airports and hotels are easy marks for thieves, who usually can make much more swiping a $3,500 laptop than a briefcase or a camera--the computer will easily fetch $1,500 at a swap meet or from a dealer who doesn't ask questions.

Computer theft is "starting to reach epidemic proportions," says Donn Parker, a security expert at SRI Consulting in Menlo Park, California. Laptop thefts rose about a third last year, adding up to losses of some $500 million for U.S. companies, estimates David Johnston, co-founder of Safeware, a Columbus, Ohio, company that claims to be the leading insurer of personal computers. "It's driving us to consider raising our rates for portables," he says. (They start at about $60 a year.)

Like a Red Chevy Camaro, some machines just scream, "Steal me." Among the most wanted: IBM's newest Thinkpads.

Coffey, the L.A. detective, has formed a consulting firm, Corporate Travel Safety, in the L.A. suburb of Canoga Park, to help business travelers get wise to crooks. Some tips: Anytime someone approaches you, be aware of your property. And when telephoning in an airport, keep your laptop in front of you by putting your feet in a vee. Don't even think of putting it in a luggage rack on a shuttle bus.

There are some high-tech countermeasures as well. If you want your computer to squeal on the dirty little rats, consider the CompuTrace software recently unveiled by Absolute Software of Vancouver, British Columbia. Says spokesman David Legg: "It resides on a computer's hard drive and periodically accesses the modem without the user knowing about it and tries to call our center." If linked to a phone line, the computer phones in its serial number and the number it's calling from. Says Legg: "Our first recovery was with a client who had a problem with internal theft. While they were interviewing one of their employees about a computer that was missing, it called in from his home." --David Stipp