Online gaming allows people the anonymity to be jerks if they want to and not face many actual consequences, whether it is trolling, ninjaing a piece of loot, rage-quitting a group because of a single wipe, or getting into a shouting match over Vent. Sometimes we carry real-life events in game with us. We have a bad day at work or break up with a girlfriend or worse, and we are unable to suffer noobs lightly. Sometimes we're rude, telling the guy doing terrible DPS he is bad and removing him from the group, as opposed to trying to help him; sometimes it is far worse.
Back in The Burning Crusade, I was in a raiding guild I particularly liked. Good progression, mostly decent people, raid times that fit my schedule well at the time -- I thought all was good. However, there was on officer who I just did not get along with. So one Saturday, she was forming a ZG raid and asked me if I wanted to go. I said no, I was dealing with something in real life and was about to log. I didn't go into details, but we had a death in the family, and I just wasn't able to really concentrate on tanking at the time. I logged off.
So a couple of hours later, I logged back on an alt and noticed they were still in ZG, so I asked what's up and how many chests they got. The officer went on a rant, just berating me endlessly, taking out their bad raid on me. I gquit on the spot -- all of my characters. Other officers talked to me later and asked me what happened, and I told them ... but I just could not go back after that.
While I am currently in a guild that suits me better, I still wish I had left the previous guild on better terms. So have you done anything in a fit of rage you truly regret, something you actually felt guilty about afterwards?