Temporarily put OS X notifications in "do not disturb" mode? A person will be sitting next to me, working together with me on my Mac, and I would like the make sure none of my personal notifications appear during that time. I would not want to lose my carefully chosen notification settings though so a "temporarily do not disturb me" would be perfect.

Note: this is for OS X, not iOS...
You can option click on the notification center icon in the menu to quickly enable or disable alerts and banners.

(Notifications are temporarily disabled and will be automatically reenabled the next day)