Some urban legends are part nightmare, part slapstick comedy. They depict an unbelievable, but realistic, series of hideous foul-ups. Talk about bad days - the ones described in these legends are really the pits!

These stories aren't about real bad days, though. Most of them are just legends, passed on orally without a shred of supporting evidence. Here are three such stories sent to me recently by readers.Daniel W. Lies of Spring Valley, Calif., heard a wacky legend about lost dentures from a fellow employee at the insurance company where he works. Supposedly a claim was submitted to request replacement of a pair of lost dentures. But the storyteller hadn't actually seen the claim form.

A woman, upon arriving home from grocery shopping, went into the bathroom to hang up a new roll of toilet tissue. She tripped in the doorway, dropping the roll of tissue, and instinctively stuck out her arms to break the fall.

As she fell, her hand hit the toilet handle just as her chin struck the edge of the bowl. Her dentures flew out of her mouth and were flushed away.

Like you, Mr. Lies, I believe this is just a variation of another improbable lost-denture legend - in which a person loses his false teeth while swimming or boating.

Another bad-day legend involving a woman in a bathroom was sent to me by Mary Stafford of Allston, Mass. A friend of hers said it happened to - of course - a friend of a friend.

A young American woman studying in Paris is invited to dinner at the home of a wealthy French boy. Needing to relieve herself, she whispers to the servant who takes her coat, asking him to direct her to the "powder room."

The room to which the butler directs her has a sink and mirror, but no toilet. Too embarrassed to seek the right room, the young woman tries to use the sink as a toilet. She slips, and not only is she is knocked unconscious - she also sets off a cascade of water from a broken pipe.

Bad day No. 2 for the American student comes when, in spite of everything, her French friend cajoles her into coming back to dinner another day. This time she sits on an antique dining-room chair, which collapses under her, crushing to death the family dog, which was sleeping underneath.

I might have believed this tale of woe, were it not for the second part, which is a variation of the legend I call "The Crushed Dog." After all, in European homes the bathroom generally is separate from the washroom. And it's just like the French to use a rickety antique for everyday dining.

I've saved the worst of the bad-day stories for last. Elizabeth Rutledge of Ocracoke, N.C., remembers this one being told in the early years of World War II. Though I was a mere lad then and don't remember hearing the story, I've heard several versions of it in later years.

A woman is bathing her two small children upstairs when the doorbell rings. Hurrying down the steps to answer the door, she trips on a toy and falls to the bottom, breaking her neck.

At the door is a military envoy, sent to inform her that her husband was killed in action in the Pacific. He knocks and knocks, having heard her footsteps, then finally goes away. When authorities enter the house later to check on the woman, they find her sprawled dead in the hallway and both children drowned in the bathtub.

Of all days for her to trip and fall coming down the steps!

Rutledge wrote that she later heard the same story, in which police officers come to the door to say that the husband had been killed in an auto accident. In some versions the children had begun to play with a radio or a hair dryer in the bathtub and were electrocuted.

Hey, I hope I haven't spoiled anyone's day by repeating these accounts of dreadful days.