Its bananas
Welcome to the heady world of airline marketing. As an illustration, if you were running a fruit and veg stall it would work like this:
Bunch of 5 bananas: $2
Bunch of 10 bananas: $1.50....but ONLY if you promise you will eat ALL of them, and you eat the first five this week and then wait at least one Saturday night before you eat the rest...oh yes, and don't throw the peel away over your left shoulder on a Tuesday unless you are standing on one leg.
Yep, it's bananas!