This is really a very surprising article on a way to get ahead in Java. The key point is to be found in the middle of the second paragraph:
Like the of thousands of pilgrims that have turned up this night to Gunung Kemukus, Sarimah is here to seek her fortune. According to local belief, the ritual here can guarantee success in business, usually for those at or near the bottom of the ladder – bus drivers, rice farmers, market stall traders and the like. Pilgrims mostly come from Indonesia’s Javanese-speaking core, but some travel days across the massive archipelago to get here.Read the whole thing; if you are like me, you had no idea that animism/Islam/Hindu/whatever mix had such practices.
But the ritual needs to be done right. First, prayers and offerings must be made at the grave of Pangeran Samodro and Nyai Ontrowulan. At some stage, pilgrims must wash themselves at either one or two of the sacred springs on the hill. Then they must find a sex partner who meets two conditions. First, your mate for the night must be of the opposite sex; and second, they cannot be your spouse. Many people believe the ritual only works if you return at seven consecutive, 35-day intervals, either the night before Friday intersects with Pon, or when it crosses with another Javanese day, Kliwon.
* from, if I recall correctly, the failed seduction scene in Indiana Jones and the Temple of Doom.