"They don't grow key limes out here?"
"No, dear. They can only grow them in the Florida Keys. Hence, key limes."
"But they're just limes. Why can't they grow them anywhere?"
"The Keys have shells mashed into the sand. It helps the limes grow."
"Can't they just put shells into the sand here?"
"Honey, let's not get into this. We're on vacation."