There are some unusual things that happen on the golf course and most of the time we don't know what to do.
We just know there is invariably a penalty - usually headed our way - and it sucks and you'll go in over your handicap. Again.
The putting green is usually one that throws up some peculiar situations but more often than not the rules are simple.
A video posted on the Instagram page @golfrules_questions threw up another interesting situation the other day.
It shows a player attempting a putt - we'll be generous and say it was definitely for eagle - trickling uphill towards the hole.
The ball stops, then slowly makes its way back from where it came - but then hits his playing partner's ball in the process.
What do you do? Is there a penalty? For how many strokes?
Well, it depends on whether you are playing matchplay or stroke play.
In stroke play, the Rules of Golf state this is a two stroke penalty for player's ball hitting a ball at rest on the putting green.
However in matchplay there is no penalty.
In both cases, the ball at rest must be replaced.
This is under rule 11.1a.
However the ball at rest was permitted to be marked while the struck ball was in motion.