after a jog in a forest, you see a white panel with portal on it, you decide to go in and you end up in a room with white panels, and a woman in the middle.. but mechanical..

Hello, test subject, I am GLaDOS. I have been working on a waste disposal system for my atomically correct human body, and you're gonna test it. In other words, you are gonna eat my crap, pee, vomit and other wastes humans make.