Some Neighbourhoods organize themselves in local committees for saving money in order to buy christmas gifts for their children, among other reasons. To achieve that, they perfom several activities such as bingoes, parades and thematic parties. Besides their primary motifs, these committes are good excuses for gathering and hanging out with friends and neighbors in Sundays once in a while.
p.s: this young lady was not preparing herself for dancing cueca in September 18th. That sunday was the dancing day and the committee prepared a Fonda Party.