Quick costs are an alternative or a system that can be used side by side with your traditional F&B menus. They are created primary from within the event itself, or can be setup under Admin > Menu Management > Quick Costs.
A "cost" for an item or service can be created on the fly then assigned to Catering, Beverages, Equipment etc.. these costs are stored within your system and can used again in the future. They can be edited via Admin > Menu Management > Quick Costs.
So for example, if you needed to add a cost to an event for "Hot Dogs" you could click on Quick Costs > Add button - then add in "Hot Dogs" as a Catering Quick Cost - this will then appear as a Catering item for your event - you can then use this Quick Cost again for any event if required.