Acronym for Highly Opinionated Older Person. A HOOP needs little provocation to tell you all about their life and the things that bother them about it. No matter what it is, they have a very specific position on it and will expound on this in paragraphs. They will sometimes ask you for advice on something and then proceed to tell you why your advice is invalid. It often seems as if their existence is based on a steady flow of complaints.
That guy talked my ears off about all his family members and what was wrong with each and every one of them, down to their political positions. Total HOOP moment.