It's supposedly good luck ...

"My friend had a gorgeous, beaded wedding dress. After getting out of the limo and heading into the church, she was standing under a tree for a moment. A bird deposited its 'gift' on the front of her gown. Inside, five women were working to get that mess out of the beads, but it was just smearing more. Finally, the wedding consultant painted her dress with whitewash shoe polish. By that time, the wedding march had played three times and everyone was beginning to wonder if there had been a runaway bride."