Bilá sobota is White Saturday. Just like on Green Thursday and Good Friday, the boys in the villages go around with their rattles. But today they stop at every house and rattle until they're given money. The money is then split between themselves.
Not sure what the point of the money is for. Maybe it's for having scrared Judas away for the last three days. Maybe people pay the boys so that they will knock it off with the dang rattles?
Again, this stuff goes on out in most of the villages. But I think that some villages may have slightly different traditions. We haven't seen any of the rattling in Prague this weekend.