Let's get one thing straight here. When it comes to videogame multiplayer matches, I am a combat pragmatist. I am not going to switch to my melee weapon just  because you ran out of ammo. I am not going to think twice about stabbing or shooting you in the back. If I have placed explosives on your vehicle I will only blow it up after it's been loaded to the limit with your friends and not before. I will not wait for you to get into a tank before I blow you up with my own tank.
 
From Battlefield 2 to Call of Duty to Killzone 2 to Team Fortress 2, I do not care about 'honor' in videogames. My aim is to help my team as much as possible, and if that means I have to take every opportunity I can get to screw your team over, then I will. That said, I do care about being polite. I don't mind if the people I'm playing with are rude and filthy-mouthed, I try my best to thank people for helping me and not explode into a ball of rage when someone messes up. I ignore trolling in the chat, whether in voice or text, and just concentrate on helping other folks instead of getting caught up in a pointless-yet-energetic argument.
 
My willingness to be helpful and rare acts of rudeness seem to have surprised quite a number of people I've played with online. Here's an example: This was about two years ago, and I was playing multiplayer on Modern Warfare 1 on my PS3. There was this teenaged kid who sounded about 15 or 14 years old on my team. As a sniper, he was camping quite a distance behind me. As for me, I was rushing forward looking for enemies. Unfortunately, I ran into three dudes and while I was able to take out two of them, my submachinegun had run out of ammunition and the last one standing had already opened fire.
 
That kid sniped the last man's head, and I was saved just half a second before death. I said  'Nice shot! You just saved my life there'  and he thought I was being sarcastic, promptly telling me to shut up. I was a little surprised by the kid's reaction, and I thought "Maybe he just wants to concentrate, he's probably looking for other targets. That's fine with me."
 
Then in that same match, the kid had moved to an indoor position and I happened to be in the same room. The boy was staring out the window, while I was behind him picking up an assault rifle from a dead player (since I was out of ammo). Suddenly, an enemy player ran into the room and charged straight for the sniper. The guy didn't seem to have noticed me, probably because I was in a corner, and I immediately gunned him down. I didn't say a sarcastic 'you're welcome' or anything like that, but that kid just yelled me for 'stealing his kill'. He claimed he heard the footsteps and was going to turn around and stab the enemy dude at the last moment, apparently wanting to make himself look badass. Later on when we were in a similar situation, he shouted at me for being an idiot after not killing someone who had just knifed him.
 
While one could say that was just a case of some troubled kid who seemed to have deluded himself into thinking the entire world is against him even if people are just trying to be friendly, there have been several other times when I'm being helpful or nice and people either reacted with genuine surprise or suspicion, as if a man saying 'thank you' or 'here you go, have fun' is a sign he's about to grief you in some shape or form.
 
Here's another story, an older one, during the days when I used to play Battlefield 2. It was common for players to quarrel over vehicles, and in this one instance I was in an attack helicopter. There were these two guys, one of them got in as my co-pilot, but the other one just shot at me, telling me to 'GTFO the heli! i wanna ride with my pal!'
 
Not wanting to deny two friends from having their fun, I got off the helicopter and said 'okay, here you go! Have fun!'
 
Then neither of them wanted to be on the helicopter. Apparently they thought I put C4s on it, and feared that I had planned on killing them the moment they were airborne. I have a lot more stories like this, but I think it's best I stop now before this post becomes the size of a small mountain.
 
I don't know how common stuff like this is, but I seem to run into strangers like these a lot. Either I'm too nice for multiplayer or there's a really large number of paranoid people who don't seem to understand that strangers can be helpful/nice too. Team Fortress 2, in my experience, seems to have fewer people like this, which kinda explains why it's currently my favorite multiplayer game. 
 
Of course, from time to time I do lapse into the jerk-zone. Sometimes when I'm in a  bad mood I say things like 'you idiots why did you put all your sentries in the same spot?' or 'which one of you morons let two engineers build sentries in front of our spawn while i was dead?', but I try my best to stay polite and helpful. It's just so strange to me when people respond to niceness with shouts and suspicion.
 
What about you? Got a similar story to tell?