There are a few times a year when a large fraction of employees are out on vacation at the same time, such as a single work day wedged between a holiday and a weekend (as happened this year on July 5). The most extreme case of this is the week between the Christmas holiday and New Year's Day, where the offices are practically empty. On these days of low demand, many services are scaled back and some choose to close entirely so that they can do inventory, perform routine maintenance, or upgrade equipment.

One of the most visible service reductions is in food service. Smaller locations (such as snack bars) are closed, and the kitchens which remain open offer a reduced menu. But just because most people are on vacation doesn't mean that nobody is watching. Here's a menu from one kitchen that was posted almost exactly one year ago:

Breakfast Roberts Waffles
Breakfast Burrito
Warm Tortilla filled with Scrambled Egg, Golden Hash Browns, Onion Green Chiles, Monterey Jack Cheese and Salsa.
Today's Soups Clam Chowder
Tomato Basil Bisque
Exhibition Station Closed for Holiday
Shanghai Shanghai
Greek Potato Salad
A delicious blend of potatoes, tomatoes, red onions, flavored with mustard, parsley, dill seed, mint and lemon juice.
Wild Greens Grill and Greens
Chef's Table Station Closed for Holiday
Pizza Specialty Pizza by the Slice
Deli Mozzarella, Tomato and Basil Panini
Mozzarella, Tomato and Basil Panini
Spcied [sic] Cranberry Turkey Salad Served on a Flaky Crossaint [sic]
Entrée Check Freezer
Grill Tuna Melt
Steak Frites