When you're sharing your screen for a business or school presentation, you don't want any notifications popping up, like a sext, a calendar notification for your therapist appointment, or a Slack DM about the problem client you're currently presenting to. You could hit "Do Not Disturb", but what if you forget? While Windows 10 has a built-in option to turn notifications off during screen-shares, OS X doesn't. The free app Muzzle fixes that.
Muzzle mutes notifications while you screen-share with Slack, Google Hangouts, join.me, and other apps, though it's currently buggy on Skype. It sits quietly in your menu bar and uses zero memory when you're not screen sharing, says its developer Bryan D K Jones.
As depicted above, the app's download page displays an endless array of humiliating notifications you might want to avoid. If Jones's fake notifications are funny to you, keep an eye out for the prank app he says he's working on, which will deliver them to your actual desktop.
By the way, the app's tiny interface includes a goofy button labelled "Mach Override". Go ahead and push it; it doesn't actually do anything. Which seems like a foolhardy joke to make in an anti-embarrassment app, so we're warning you here.