It can be aggravating when you've done pvp for a very long time and what seems like basic guidelines to you are completely alien to newer players.
That's where all of my rage comes from.
I really only get mad in Huttball, and occasionally voidstar.
Voidstar I only get annoyed when I'm capturing an objective and rather than use roots and knockbacks to keep people from me, my teammates run up and click on the door as if it will make it go faster having more people do it. That's always a telltale sign of a newbie.
The rules of thumb in huttball are what really drive me crazy.
The most obvious ones are the ones I see violated the most:
Don't run through the fire
Don't be a ball hog.
Countless times I've seen people running through the fire with the ball in hand, thinking it'll be ok. And countless times I've been perched above the ball carrier who is getting whaled on by five enemies while I keep repeating "Pass," but all he does is continue trying to run and jump a little. Unnecessary jumping is also a telltale sign of a newbie, because it slows you down.
I cannot stand ballhogs in huttball. Passing the ball is SO advantageous, but often people just don't do it. I once was waiting on the goal line while the ball carrier was being mauled by three or four guys, but he refused to pass the ball to me, which resulted in a lost goal.
So that incurs my rage.