It is unlucky to kill a spider, spill salt or break a mirror. Two is company, three's a crowd. It's interesting to note that although many superstitions are based on a belief in charms, omens, signs and the supernatural, some superstitions are thought to be teaching tools. For instance, the saying that a girl who takes the last cookie will be an old maid, may be a way of teaching young girls manners. So remember, despite what you were taught, there is nothing to fear on Friday the 13th.
Today is a day like any other day.
Knock on wood.