I don't mean for this to sound as if I think I'm sitting on my high horse because that's certainly not the case, but I've never really had a meltdown on the course. Sure, I cuss about a bad shot at times and have slammed my driver before after that slight draw I imagined turned into a massive hook out of bounds, but I just don't ever really have the urge to throw clubs or anything of that nature. I deal with my frustration differently, and that's by mentally just shutting down. I don't talk to any one or say anything at all, I just go through my shot routines and hit the ball. It comes across as if I'm holding my composure really well, but I'm not. My friends have commented about how I never get mad about a bad shot and how they wish they could do that, but the truth is I don't deal with it any better than them. On the outside I seem calm and focused, but when I'm addressing the ball my thoughts are still on that shot that I hit OB... I can typically dismiss a few bad shots and regain focus pretty well. Rarely do I reach the point of completely shutting down, but when I do you can pretty much guarantee my round is going to continue to be terrible.
My brother-in-law is completely opposite from me, and he'll throw anything he can get his hands on. The sad thing is he's a pretty good golfer, but one bad hole can ruin his entire round. He's broke several wedges over his knee, and sent a few more to the bottom of ponds as well. Not to speak poorly of anyone who acts similarly, but I find him very distracting to play with and get tired of constantly having to compliment his game in an effort to keep his attitude positive for the sake of my own concentration.
In high school there was a kid from our rival school that was well known for acting like a psycho on the golf course. He was a pretty decent golfer, but just went nuts over bad shots. One day on the last hole he hit a ball in the woods and went to sling his driver. Well he held it too long and threw it right at his playing partners, which included me, my teammate, and a teammate of his. We all ducked, but his teammate didn't make it in time and the head of the driver crushed his nose. My teammate cussed him up one side and down the other, with some assistance from me, while we tended to his teammate and called for help. That kid was kicked off of the team that day.
Getting mad on the course is one thing, and we all do it. When it reaches the point of being dangerous to others though, that crosses the line. Also, I think one of the reasons I handle it the way I do is because I try not to let my behavior affect the others I'm playing with. I know how much I hate playing with my brother-in-law when he acts that way, so I just shut up and keep to myself. It doesn't help me any, but I like to think that it doesn't make my playing partners lose focus.