AutoMute

All I can think of when I see this is this video (takeaway: ALWAYS silence your mac in class!):

Hello Product Hunt! This is my first official hunt. I choose AutoMute because it has saved my butt so many times in class and meetings. You select certain wifi networks, such as your work or school wifi network. Then every time your mac connects to that network, it is muted! Just make sure is on when you restart your computer. Thank you @lorenzog4545 .

Nice! This will go perfect with my notifications silencer app http://jmitch.com/serenity