Oh, I've luckily kept my cool while driving karting and rallycross. However, there was this one time when I was running second the whole weekend (me and another guy was completely dominant, but I never could get passed him). This was a karting event, so it took place from Friday to Sunday. However, after all the heats, and the prefinals had been done, it looked pretty much set who would win, and who would come second. But that was until the guy starting in third decided that his only chance to get higher, was to turn me around. And so he did, race over very, very early in the final... I ran to our tent, got my competition license, and ran to the stewards. Was told to wait, and cool down. So, the race was over, and I was allowed to talk to the leader of the stewards, who fittingly sat there with some waffles and a coke...
All he had to say was that he didn't see it, but knew it was a race incident. I asked how he could know it, oh that was simple, we had fought so clean the whole weekend... Except, we hadn't.
I then pulled out my license, put it on the table and said "I'm not doing this anymore", luckily someone took it from me, and said that I would also loose my RX-license if I did this. So I kept it, but swore to never race a race with that guy as the chief of stewards. I never did either.
This was in a time in norwegian karting when the driving got uglier and uglier for each weekend, and getting that response from the steward, just tipped me over. I was shaking in anger, and still, I get angry thinking about it, 5-6 years later. I can't understand that I dared either, 15yo and giving up my license. Guess I was angry...
But I never touched that guy, on or off track!
Simracing is a different matter, I've totally lost it once, was bumped out of the way, and got I my revenge, and never been so close to a lifetime ban, ever.