My friend was in top 4 at a cities, and he wa beating his opponent 5-2. His opponent had 1 card in his hand, and then he drew 7 cards out of desperation. The judge gave a prize penalty and my friend, won, advancing to Finals. The opponent swore and then stormed off.
My other friend was playing at States, in top 8, he faced a Magnezone/Feraligatr/Kyurem deck. The kid was really proud of his rouge, so when my friend barely beat him, he stormed off, crying and didn't even take his packs. The judge looked at the packs, then slipped them into his pocket and walked away.
At league, I was beating this nooby 6 year old with his horrible rouge and I took 2 prizes with Virizion(I was playing corners)
Then I played N and once we shuffled, he drew his hand +1 card and started his turn. I tried to explain, then got the league leader and we worked out. But as soon as she walked away, he did the same thing. The other league leader came over and asked us if we wanted to stop, and get equal marks and we did. The kids mom made him play 3 games of battleship to calm down before he played again.