I had a parent yell at me once immediately after a basketball game about why weren't we pressing constantly. Berated me for 5 minutes. I just stood there and let him look like an ass. When he was done, I politely reminded him it was 3rd and 4th grade players, and that you weren't allowed to defend the ball in the back court.
I had another parent yell at me about not letting the kids shoot 3s and not spending the whole practice working on the offense. I had his son, who he was alluding to with the comment about the 3s, shoot 10 of them... 0-10 and he didn't even hit the backboard or rim on any of the shots. I also explained to him that it does no good to teach kids to run an offense if they have no concept about the basics of the game and the complete inability to perform the basics, such as shooting, passing and dribbling. Which is why I spent most of every practice doing drills/games designed to teach kids those three things.
As for officials, I will fully admit, I have yelled at officials before. But it has been paid, certified officials and it has generally been for something they missed that was (somewhat) safety related, such as an obvious elbow to the head. However, it doesn't happen very often. I generally sit fairly quietly and comment to neighboring fans on why what they are yelling is either right or wrong. I watch a lot of AAU ball, and the parents can get vicious. The funny thing is, based on also watching a lot of HS ball, the officiating at most of the AAU tourneys is not markedly worse than most HS games. The biggest difference is using two instead of three officials. So I give them a bigger break.