Well, there were a few games (with release Vayne), after a bit of a headstart in early game, no one else would get kbs other than me. So, my friends income was all creeps, because in team fights would be all mine. Somehow we managed to lose. I ended that game 45/15/1, and it was kinda upsetting.
Enemy team realized they couldn't win teamfights, so they started pushing 3 lanes simultaneously (spell check? =P). I can't remember which champs they had but they were mowing creeps and denting turrets quite fast.
We tried having me go against solo (would get him killed but I didn't have the mobility to reach other lanes in time). My underfarmed team couldn't hold 2 on 2, and they did take w/e chances they could to end my killing sprees for large $$, even if it'd get some of them killed in the process.
Lately if I feel I have enough advantage over enemy team, I try to leave some kills for mates and it seems to work better o.O