If you want to imagine a world where on Xmas morning presents open children, pigeons feed us & other madness then snort a foot long line of kethamine before freebasing Dennis Hooper, alternatively if you don't fancy that have a look at these.
Via Kotaku, the screenshots show how Alice looks when she enters Hysteria mode in Alice: Madness Returns. And the video below shows the mode in action (35 seconds in):