Make no sudden moves. Don't walk out with anything too obvious, like the Pikachu on top of your monitor. Save that for last. Stick to the confidential memos and product plans. Nobody will miss those.
Attendance is mandatory.
At the all-hands, your brave chief will explain how they ran out of quarters and couldn't feed the meter. And then someone from editorial will burst into tears and there will be hugging. It goes on like that for hours. Toss your few remaining personal effects into the shopping bag that's stuffed in the back of your file drawer for just such an occasion. Keep the exit interview short, and cash out your vacation time while you still have the chance.