4/10. It wasn't just one parent, it was ALL of them watching a particular game. I didn't referee any differently this game, but none of them could handle the fact that because I also played soccer I'd let a little physical contact go. They wanted me to call a penalty every single time one player touched another. It's soccer, people! Contact happens! I finally had to stop the game, call over both coaches, and tell them to calm down their parents or I would send them all to their cars (something I was well within my rights to do). They calmed down, or at least grumbled low enough that I couldn't hear, and the kids finished the game. One of the parents took the issue to the league officials. I explained what happened, and they told me I was correct.
5/10. I was a volunteer ref for one night only at the elementary school near my high school for Floor Hockey night. I live in Canada so we had some pretty hockey passionate kids and parents playing (Yes, parents were allowed to play and high schoolers had to ref. Only one school staff was present. It was a disaster from the start) It was fine for the most part of the game when one little kid kicked in the puck. This one middle aged dad was livid and yelled at me to disallow the goal. I told him it was a for-fun game and I wasn't even keeping score and this resulted in like 5 parents screaming and 3 actually grabbed their kids and left.
6/10. I referee hockey and I was refereeing a game in a tournament when this happened.
To make this easier, I will call the 2 teams: white team and black team.
To anyone familiar with hockey, as a referee, I must call penalties when players break the rules. Well early on in this game, I was calling a penalty on black team and after I had assessed the penalty to the player, white team's coach started to yell at me that the other teams player should be ejected from the game because he was trying to injure white teams players. I calmly told the coach that it did not look intentional to me and that the kids are only 6-7 years old and not playing at the competitive level so they might not have fully developed skills. White team's coach was furious and started to yell swear words at me and I assessed him a penalty for unsportsmanlike conduct (this is correct procedure to follow as an official).
After that, the white team's coach was calm for most of the remainder of the game up until 3 minutes left. One of the white team's players tripped and slid into the boards hard and hurt himself and the coach thought I should throw out another one of the black team's players. Once again, I skated over to him and informed him that there was no penalty and that the white team's player just tripped. This would turn out to be the last straw for this particular coach. He opened up the door and stepped out onto the ice so that we were face to face and he started to yell at me that I wasn't doing my job properly and that his players (white team) were getting seriously hurt.