I'll divulge what is surely my worst rules violation. It was a high school golf match early in my senior year (we were playing Medfield, MA, if anyone knows the area). I was playing in either the 2nd spot (I played anywhere for 1st to 4th that year, mostly based on matchups and partners), and I had already won my match handily. My playing partner, the only girl on our team and one year younger than me, had her match going down to the wire on the last hole.
She hit her tee shot into the first cut of rough, well forward of her opponent. As he stood over his ball, taking practice swings, on one of his last ones he made contact with the ball, and hit a dribbler into a nearby bunker. He needed to win the hole to tie the match, and, after than shot, was effectively dead.
In what will surely go down as the worst brainfart of my golfing life, I came up with the idea that since his intent was not to hit the ball, it should be replaced (using the logic/rationalization that if you accidentally knock the ball off the tee with your club, it doesn't count). He replaced the ball, knocked it close, and two putter for par, while she, who agreed with me on the ruling, was a little out of sorts and missed the green badly. She bogied (or worse, can't remember), and her match finished in a tie.
Of course, that came back to bite me, as we ended up losing to the other team by a half of a point, a half a point we would have won if it weren't for my screwup. If I actually knew the rules, I would have known that the guy (who I found out later knew the correct ruling) should have played the ball lying 2 from the bunker, and there's about a 99.867% chance he would have lost. Instead, he tied, and our teams tied. Fortunately, it didn't hurt us at all in the grand scheme of things. We finished 8-8, which was just good enough to get us into state sectionals, and we ended up shocking a whole lot of people by making it to the state finals.
Last I heard, she's playing college golf at Ithaca or Iona or something, and he's still a short little ass. And I still don't know the rules as well as I should, though I've vowed to study them like I'm trying to pass the bar the next time I play a tournament. As far as I know though, I haven't broken any rules since.
Y'all are likely I even divulged that. I don't think I've ever told anyone. Congrats.