Had an invite from a friend to a mission (not sure the name, but the one where you destroy all the garbage trucks, and then the gang after), got into the lobby and found that he had gotten kicked from Xbox Live, so I hit the button to leave the lobby (or so I thought) and go to get something to drink. I come back to find that it hadn't put me back in my invite only game, but had left me in the mission, where some other guy had joined and was almost done with completing it. So I get in my car and go to help, there is only 1 truck left so I destroy that, and I only get to kill 3 of the gang (the other player had already wiped most all of them out). The gang boss runs, and he goes and kills him. Now, somehow, even though he did almost the entire thing himself and I only joined in at the end, I get the full $20,000 and full RP, he gets half of that.
Not sure why that happened, but at first I feel bad...And then he messages me with "HOW ????LOSERNOOOB!!!!!!!" which kind of ticks me off, so I reply back "What do you expect? Leaving me to do the whole thing myself while you jerk off in a corner the whole mission, if it was up to me you would have gotten nothing." Oh, the amount of rage texts after that, so funny.