For me it is keeping my equipment pristine. I wipe down my club after every shot, and after the round I thoroughly clean them.
Depending on the weather I clean my grips weekly, as well as wash my golf gloves. When a glove gets to be a bit worn, I use that for practice and the new glove for play.
I also look for golf balls once a week after I complete a round of golf. I don't need any golf balls (I have about 50 dozen), and I also don't need to be fighting with briars, poison ivy and mosquitos. Yet I am compelled to search.
I also clean/polish my shoes regularly.
What are you OCD about...or should I say anal retentive? :-)