Lost a game that my friends and I could have easily won, and actually were winning. The deciding point was my top and jungler, my friend and brother respectively, fed Vayne. :'(.
There were a few team fights where I called to back but everyone else got too greedy, so that turned it around just ever so slightly, since I was able to easily push lanes into the inner turrets and then let the minions do the work while I helped my team.
This was on normal, so it didn't really matter too much, but even still. It was a game that was definitely in our favour.