Surely you have suffered this same situation: You are giving a really good presentation, with a fantastic slide deck in your shiny MacBook, you are dominating the stage and people are nodding at your witty insights… and then an email notification appears in the top right-hand corner of the screen, followed by a FaceTime call from your other-half…. Noooooo!
A good way to disable these notification is to ⌥-click (option-click) the notification bar:
In that way, any notifications handled by the notification bar are not shown. Once you are ready to receive notifications, simply ⌥-click (option-click) again. Et voilà!