A SOCIALITE we know had an unnerving experience when she was quite literally flashed at during an urgent visit to the ladies' room of the Mandarin. The dastardly offender, armed with camera of course, was making no apologies. It appears she had just this sort of thing in mind when arriving in Hong Kong a few days ago from Australia for her 17th visit. Seems the Aussie has never seen loos quite as opulent (and quaint) as those in service at the Mandarin. And after a visit to some of the Chinese toilets, which, er . . . required perfect putting skills, she decided it was time to take a snap or two for the family album. Evidently the snap-happy Aussie assured our informant, and the other bemused patrons of the blue flowered Chinese bowls, that after 67 years of toilet experience she never thought the ladies' room would hold any more surprises for her. Until Hong Kong, that is . . .