I am ONLY HOPING that Madonna was going as her daughter as a joke, and not some desperate attempt to show that at 50 she can fit into a 13 year old's clothes... as the Daily Mail points out that all the stuff she's wearing is actually Lourdes'.
But what else can she be? Overage Zombie Harajuku Girl from Hell? I thought that spot was taken by Gwen Stefani. BaaZING!
So I just looked Purim up on Wikipedia, and it turns out it IS Jewish Halloween. Who knew? Wikipedia knew, bitches! So that means that Jessica Alba did too! Suck on that!
Purim is celebrated on the 15th of the month, known as Shushan Purim. Purim is characterized by public recitation of the Book of Esther (keriat ha-megilla), giving mutual gifts of food and drink (mishloach manot), giving charity to the poor (mattanot la-evyonim), and a celebratory meal (se'udat Purim); other customs include drinking wine, wearing of masks and costumes, and public celebration.