What does HAGS atand for?
HAGS simply means, Have A Good Summer. Commonly written in school yearbooks.
What do I do if I ran out of magic to use my lens of truth and don't want to reset time or waste time to get more magic in termina in Majora's Mask?
Purchase a green potion, either by visiting (and first assisting) the hags at their magic potion shop in Woodfall, or visiting the Trading Post in West Clock Town. The latter is more expensive than the former, though green potions are more readily and easily available if the hags' side-quest has not been completed in your current timeline.