Two nuns turn up at the fruit market and ask the veggie man

Two nuns turn up at the fruit market and ask the veggie man for 120 cucumbers. The guy advises: “Sisters, if you buy 3 crates, that’s 150, you’ll get a 25% discount!” The nuns look at each other, and after a prolonged period of thinking one whispers to the other: “We could eat the 30, I suppose.”