Well, you see, for Ryanair it's sort of like that guy in Greek mythology who had to keep pushing a boulder up a hill only to see it roll back down again.

They finish off one bag-full of letters with your quoted two-word reply, only to find that there are three more bags of post waiting to be answered. And once the next bag is done, that number has risen magically to five. And when the next bag is done, that number has risen magically to 7. I think you get the idea...