You may have noticed that all the sandwiches with mustard at Jimmy John's feature Dijon mustard instead of the standard yellow mustard found in most delis. The reason for this may seem surprising, but it all makes perfect sense when you delve into the chain's logic.

With only one kind of mustard available at the restaurant, the employee making your sandwich won't be fumbling around in a container of similarly-labeled condiments. This cuts down the time it takes to get sandwiches out to hungry customers and gives them the quick but friendly customer service they want.

Despite Jimmy John's mustard preference, you can get yellow mustard on your sandwiches if that's the only kind you like or if you simply have a craving for it. The chain has a secret stash of yellow mustard packets, and though they may not be where you can see them, you can ask for them.