Use food pantries to extend your food budget. This is particularly important if you have kids who eat like there is no tomorrow. You can also sign up for meal assistance with your kids' schools (though this depends upon how much household income stops during the shutdown -- all verse just some, very case specific for meal assistance).

Many business offer free items to furloughed federal employees. Some offer a free meal, some offer pet food. Take the help where you can.

And once you do get back pay, don't forget who helped you out. Make donations back to the food pantries, patronize the businesses who helped, thank family and friends who helped.