Today, September 13th, is Defy Superstition Day.  WeekendNotes.com says:

…if you’re one of the many who have superstitions you can’t seem to shake, this is the day you can let go of some or all of them by doing the exact opposite of what you’re told you should do regarding them.

They also give a few superstition-violating suggestions, which you may or may not have heard of:

• volunteer around black cats
• go out the same door you came in
• pass someone on the stairs
• change your sheets on a Friday