Chalk another one up for the "I hate randoms" tally, this is something that actually happened a few hours ago. Also, I don't have the record or a screen-cap unfortunately, as LoLRecorder has been buggy, and I couldn't be bothered to see if it needed an update. So you'll need to take my word on this, but chances are this probably happened to you at least once.
So today as almost always nowadays my friend and I need to queue with just the two of us, as our third has been AWOL for a few weeks now. I know he isn't dead, since I usually see him playing Warband for hours upon hours. This time we got a fairly cocky Nocturne, who was confident from the get-go that we would easily win. I don't mind that, sometimes (SOMETIMES) these people can be decent as they've got comfortable enough with their champ that they can be cocky. Early game should have been a hint. From the beginning he wanted to gank the solo Lux who was getting a little cocky in bot lane, pushing out a kinda far on her own, but since we had no stunners, it was kind of hard to get her trapped to kill. He still tried though by trying to flank and failed from by their tower. He didn't die, so we brushed it off at that point.
As the game progressed, we were doing fine bottom lane, as he seemed to be getting pushed fairly hard against his opponent (Darius). He first he died to a creep in jungle to try to catch up, then after as he got back to the lane he rushed Darius and tried to fight him near tower, which as you can guess ended up with him getting killed. He then proceeded to jungle almost all the time, only getting creeps when they got close to his tower, letting Darius level and farm unrestrained, and Nocturne again died to another creep. Due to this and his utter lack of calling any sort of MIAs we started to get ganked by the whole team, without a Nocturne in sight to try to help. He still claimed we would win this. When we called him out on both counts, he stated he was "just having fun" and that we would still win. Based off of his previous and current behavior and his utter lack of willingness to help us out, we decided to troll him.
After our lane got pushed to base, we went to jungle and cleared that out, we also managed to catch Darius at dragon in time to kill him, but not quick enough to get dragon, as his friends quickly tried to run in to take us out, but we both managed to escape. From there we taunted him (Nocturne) a bit, and used the same tactics he did to (not) help us, and turned that on him - he wasn't happy. He started to blame us in chat and say that it was 3v1, that we were no help and a bunch of other nonsense that I didn't bother trying to remember - yet when he was called out on what he did and said previously, he remained silent for another 5-10 minutes before continuing to rant again. The funny thing was though, both of our scores were better than his. While we did his tactics, we still ganked and killed them every once in awhile, waiting for some of them to be alone, or just with a part of the team and hitting them hard.
Since we already knew from the lack of teamwork that we weren't going to win it, we decided to just "have fun" and play things out to the end. We managed to delay the inevitable for quite awhile before they finally took the base down and we lost. Expecting an exchange of words at the end of the game with more insults, but he had already quickly left before we could get to the stat page.
TL;DR - Don't troll your team and not expect them to do it back.