Life Lesson
When you give Zora 500 Rupees and he gives you 1, 5, 20, 50, or even 300 rupees in return, this is called a Life Lesson. One hopes that although Link may have lost a large chunk of his rupees, he still gained at least something in the process, which is presumably where the term “Life Lesson” comes from.
Can also apply to Bottle Vendor since he charges 100 rupees and could potentially hold 1, 5, 20, or 50 rupees.