If you're planning a picnic, you'll want to be sure you have the whole nine yards, which means "everything." So make sure to bring a basket, a blanket to sit on, lots of food, cups, drinks, and silverware.
The phrase is often used in the expression go the whole nine yards, which means "go all the way" or "go all out." Lots of different origins for it have been suggested, from the amount of fabric needed for a wedding dress to the volume of concrete available in a standard concrete mixer. None is accepted as definitely true, and to make things more complicated, there was originally a variant the whole six yards.