Box social is a term for a social event that was widely used in the early 1900s with varying definitions in Canada, the United Kingdom and the United States.
In the U.S. state of Vermont the tradition is that women decorate a cardboard box and fill it with a lunch or dinner for two. The men bid on the women's boxes anticipating a meal with the woman whose box it is. Generally the boxes are anonymous, so the men don't know which woman belongs to which box, nor what the box contains, the mystery and sometimes humorous results adding to the fun...
Sound like fun.