Malware, Reddit and Google Analytics
This is what happens with your traffic when one of your sites gets infected by malware and therefor being "blocked" by google. From a daily count of 200-300 visitors down to 0-2 visitors per day. But it's a funny graph to look at.
And this is the awesome thing that happens when one of the posts of the same site as above is posted and gets popular on reddit. From a stable 150-200 visitors per to a huge peak at 20 000. Such a big difference that the rest of the days looks all flat.