Watch out for ladders and leave loose change on the sidewalk, today is Friday the 13th.

Historically speaking, as a day of the week, Friday was generally considered to be an unlucky day, but when you add 13, an unlucky number, together with Friday, an unlucky day, you have a double dose of disaster waiting to happen.

This unusual day has prompted many out-of-the-way explanations for its conception.

Friday had a bad reputation even in the days of Pagan Rome where it was execution day.

It was originally a day of celebration in many heathen cultures and was vilified for this reason by the early Christian church.

Sailors also have hard feelings for Friday and refuse to launch boats on that day.

One hundred years ago, the British government sought to quell once and for all the widespread superstition among seamen that setting sail on Fridays was unlucky. A special ship was commissioned, named “H.M.S. Friday.” They laid her keel on a Friday, launched her on a Friday, selected her crew on a Friday and hired a man named Jim Friday to be her captain. H.M.S. Friday embarked on her maiden voyage on a Friday, and was never seen or heard from again.

Many cultures feel that 13, the devil’s dozen, is a particularly unlucky number for dinner parties. The belief is that the first person to rise from a table of 13 will die within a year.

One explanation for the taboo comes from the number of people present at the Lord’s Supper, which of course, culminated in betrayal. Christ was also crucified on a Friday.

The Norse also have a tale about a dinner party in which 12 gods were invited to a banquet in Valhalla and Loki, god of mischief, was snubbed. Angry at being left out, he showed up anyway, bringing the number of guests to 13. Loki, true to form, incited the murder of one of the most beloved gods at the table.

The stigma associated with Friday the 13th has only occurred within the last 200 years, and has no cleared defining moment of conception. In recent years, the physicians have made their mark on Friday the 13th history by coining the term, Paraskevidekatriaphobics.

While not easily pronounced, it can be defined as people afflicted with a morbid, irrational fear of Friday the 13th.