The puritanical Wahabi form of Islam may be the legal code of Saudi Arabia but a Jedah furniture store is selling love nests that would inspire blushes in a Paris bordello.

Four velvet canopies flare like tense cobras over the round waterbed. Integrated into their chrome-plated bases are stylized porcelain pheasants. Elsewhere around the 15-foot diameter are a built-in stereo with controls within easy reach from a reclining position and, in case anyone missed the point, lights that play upon strategically placed mirrors.

The contraption may not be to everyone's taste in this sexually conservative kingdom. But it is prominently diplayed along with several other similar creations in a big window on one of Jeddah's main commercial streets. In the open like that, the only thing that really seems obscene about it is the price: nearly $23,000.

SAUDI ARABIA, the seat of fabulous wealth suddenly acquired and swiftly spent, is full of such incongruities. What, for example, can the visitor make of signs all around Jeddah seemingly urging nighttime marijuana consumption in a country that forbids even beer on a hot afternoon?

"Sleep high," they say, intersection after intersection.

Inquiries reveal that the signs are only advertising the wares of a local mattress and bed company whose publicity agents apparently were unware of the full range of meaning in their work.

Much of the incongruity stems from Saudi Arabia's rapid growth in the last few years. Jeddah, for example, had ballooned from a port of about 600,000 five years ago to nearly a million today.

Driving down the street, you have to look hard to spot the delicately crafted latticework of traditional Gulf Arab balconies on the few remaining old Saudi houses. All around them rise concrete towers, in said contrast to these reminders of an earlier, more graceful period in Jeddah's history.

THE SWIFT EXPANSION has, of course, brought along some problems. New residential neighborhoods are going up so fast that municipal services cannot keep up. As a result, residents pay about $100 for a truckload of water delivered to their homes in some of Jeddah's highest-priced areas. Others buy their own generators because the city cannot yet supply electric power.

It is not for lack of trying. Jeddah authorities expanded one street near the airport into a four-lane expressway to handle the growing traffic three years ago. Already it is closed and a foreign construction firm is busy building a flyover to divert some of the cars entering and leaving the terminal.

Main streets are wide, California-style, in Jeddah's newer quarters. As you purr up a ramp in a heavy, air-conditioned Detroit behemoth, you can imagine yourself in San Diego before the energy crisis. But on closer look, the driver has slipped his foot out of his sandal and the sight of that bare, brown foot on the gas pedal brings you back to Saudi Arabia.

To an American accustomed to associating late-model Buicks and Oldsmobiles with home, the Saudi driver's white disdasheh robe and red-checkered headdress also seem out of place. In addition, Koranic chants are coming out of the stereo radio instead of the top 40.

Many of the drivers and other laborers in Jeddah are not Saudi. Unofficial estimates say a third of the population of Saudi Arabia is foreign, up to 70 percent of the work force.

On a construction site, therefore, it is not unusual to see a blond foreman from a West German contracting firm running a work gang composed of Pakistanis whose payroll accounts are kept by Egyptians.

Guests at the new Jeddah Sheraton Hotel find almost the entire working staff comes from the Philippines and the supervisors from Lebanon. At the Intercontinental in Riyadh, an American diplomat who tries to show off his incipient Arabic to a visitor when ordering lunch discovers the waiter is Bangladeshi whose only Arabic is a few verses memorized from the Koran.

The influx of so many foreigners who have to cope with Saudi Arabia's strict Islamic code has created problems, like that of the Filipino room boy who complains, "I don't like it here -- no women, no wine."

For most, however, it is a case of enduring a two-year contract for the prospect of returning home with enough savings to be rich men for a while.

With the bank account in mind, they swallow hard and drink nonalcoholic beer that seems normal for the first mouthful, then for the rest of the bottle leaves a mealy aftertaste. Or they go along with the waiter who asks with a straight face if diners prefer their unsweetened grape juice red or white.