Friday the 13th occurs when the thirteenth day of a month falls on a Friday, which superstition holds to be a day of bad luck. In the Gregorian calendar, this day occurs at least once, but at most three times a year. But "13 dreaming dolphins" aren't afraid of number 13. We remember a phrase of American film actor Groucho of Marx: «13 persons behind a table can be unhappy number if you have prepared only 12 cutlets». As has shown life it is number is happy for us. Therefore on August, 13th (despite that is Saturday) we invite the friends to arrange a cheerful holiday "Friday the 13th". Presence of black cats, collecting of the broken mirrors and other attributes is welcomed of "black Friday"! Let failure pursue garbage...