Why serving black food
Athenaeus,
we have great fireworks on June 24, but as far as I know nobody jumps over them here:D
As my friend explained to me, the Summer Solstice was originarily a Celtic festivity. Since it couldn't have been accepted as it was by the Catholic Church, being a "pagane" feast, was assimilated to the nearest catholic festivity, St. John the Baptist on June 24. (Something like that, I suppose, happened for Halloween. The Day of the Dead, in the Catholic calendary, is on November 2. It's mainly a religious celebration and we don't dress up...but we use to make for luck sweets like "Dead Bones", "Dead Shoes" and so on)
As everybody knows, before the Summer Solstice the days become longer and longer, and after it they become shorter and shorter. So, the solstice night was considered by the Celts the time when the two primary principles, the Light and the Dark (that is, the Good and the Evil) meet each other, and everything can happen. This is the reason why it is considered a magic night, and this meaning remained also in the catholic tradition, referred to St.John's night (in example, it was believed that the dew collected during this night had magic properties like curing many ailments or finding a husband to the girls).
After the Solstice, the nights become longer and longer, meaning that the Dark gets the upper hand over the Light. So, rituals must be made as "apotropaics" (the word is by my friend, not me!;) ) to chase away the Evil. Eating black food is one of them.
I also heard that here in Italy, but probably everywhere, there are many exoteric sects that organize get-togethers and celebrations for the Solstice night. On the other side, here in Genoa June 24 is simply the Patron Saint feast: we have a holiday from work, fairs, amusement parks, fireworks but nothing magic ;)
Pongi