When a website crashes, usually due to owner neglect. Named after an infamous non-event on popular British web comic Dog Egg, where the writer lost track of episodes during a series of emo related episodes due to be released during 'emo week'. The site spectacularly crashed and has never been fixed properly; Dog Egg even missed his 200th episode anniversary due to this fault.
Dave: Just checked that website and I'm getting php error messages ALL OVER IT.
Simon: Dear dear... All gone a bit emo week, hasn't it?
Mark: Holy christ update your website before it all goes emo week!
Adam: I can't be bothered...