BY DESIGN : Born to Be Wildly Underdressed

The Place: Thunder Roadhouse, a motorcycle-themed restaurant, 8371 Sunset Blvd., West Hollywood; (213) 650-6011.

Atmosphere: A casual mix of curious, gawking, tourists; hip yuppie bikers, and scowling, Hell’s Angels-type bikers. Both types of bikers perform identical arrival rituals: Pull up in a deafening roar, peruse the other bikes parked outside, then swagger coolly into the restaurant.

Serving-Up Style: Cocktail waitresses wear black hot pants, black tank tops and ‘70s-style turquoise jewelry. Waiters wear “Thunder Roadhouse” T-shirts with black shorts or black pants.

Customer Style: Yuppie bikers wear jeans, T-shirts and sleeveless leather motorcycle vests. The hard-core bikers are evident by their fully exposed beer bellies--only partially concealed by leather vests and leather pants. They wear motorcycle boots or cowboy boots. Biker chicks wear bra tops, snug jeans, sneers.

Hair Apparent: Yuppie bikers favor short, fashion-boy dos or neat ponytails. The hard-cores like long, straggly ponytails (often with sweaty, bald pates), ultra-hairy nestlike beards and mustaches--some accented by a skinny beard-braid down the middle. Biker chicks’ hair come in two styles: long and stringy or wild lioness.

Accessories: Motorcycle helmets, chains, medallions, impenetrable wraparound sunglasses that make one look like a jumbo fly, tattoos, cigarettes, mustache and beard combs.

Cardinal Rule: If thou art a nerdy tourist, thou must stand outside in front of a huge Harley and poseth with thy hands on thy hips, thy countenance grim, whilst thy friend snappeth thy pictureth.

Observations: Conversation is minimal among the hard-core, who alight like huge birds at the bar, sit silently with their beer and cigarettes, and move only infrequently to rub or comb their long, bushy beards. Occasionally, they peer from beneath their grizzled eyebrows at passersby.

Overheard: “There’s something about that bull-like quality in a man that’s attractive . . . as long as they don’t sleaze all over you.”

Parting Thoughts: “There’s a difference between the yuppie bikers and the Hell’s Angels-type bikers,” a cheerful waiter said. “The yuppie bikers tip really badly.” And the Hell’s Angel’s bikers? “Well, they tip really badly too.”