Again, no lectures! For quick weight loss before a big event the three day diet shifts a few pounds (although some will be water, so will go back on, but for holidays it's a quick fix).
http://www.webmd.com/diet/features/the-3-day-d iet
It's a complete and utter fad diet and shouldn't be followed for more than three days, but it does have good effects usually.
Low carbing for a week also helps shift the pounds rapidly but can leave you feeling a bit crap, so be careful! The Atkins diet and South Beach diet are classic examples.
Finally, the best route I've found is to go vegetarian for a week and fill up on home made soups, bean chillis etc. For some reason beans (not in tomato sauce!) always seem to have a positive effect on my weight.
And drink a few cups of green tea a day. It has a slight diuretic effect and boosts your metabolism a bit to help shift the pounds (and chocolate just doesn't taste same when washed down with green tea rather than coffee!)