I would assume that a coffee party is simply a party where coffee is consumed, perhaps like any other type of party but with less alcohol. According to the Guinness Book of World Records, a coffee party is a party where every attendee is given a slice of cake and a cup of coffee. There is actually a world record for it, too. The previous record was broken this weekend to much fanfare in Cologne Germany. The koffeeklatch was held by German company Kruger Kranzchen and involved 8,162 people. The previous record had just 4,585 attendees in London in 2008.
No statistics were given on the amount of coffee or cake used. Assuming an 8-oz serving of coffee, somewhere around 510 gallons of coffee may have been served, along with the equivalnt of 511 bundt cakes’ (a bundt cake usually serves 16 people with small slices) worth of cake.