The Manchester Derby got... a wee bit contentious after Robin van Persie's late free kick was deflected in to give Manchester United a 3-2 win. And by 'contentious', I really mean 'depressingly violent'. During the United celebrations, Rio Ferdinand was struck by an coin (gif via bubbaprog).
That resulted in quite a lot of blood (from 101 great goals):
Football fans can be very unpleasant when they're riled up. Consider how much fun the match was, it's a huge shame that it had to end like this.