Backstory: A friend of mine plays golf at a country club and is allowed to bring guests. He brings me along and I really enjoy going because the guest fees are rather inexpensive and the course is a lot of fun.  

The Idea: A marketplace for golfers to meet each other and bring guests to their country club.

Deep Dive: You would give golfers the opportunity to buy guest spots with country club members in order to play at different golf courses. Country club members would be able to list their guest passes and non members would be able to purchase spots.

Validation: People are becoming more comfortable meeting random strangers with uber/lyft. This also allows new golfers an expensive way to sample a premium course.

Monetization: You would take a small fee from each transaction. Additionally you could provide leads to those golf courses for a fee.

Steps to Launch: The best way to start this is to be a member yourself or have a close friend who is willing to try this out. I would post on facebook or craiglist to see if there is any interest in someone tagging along with you.