You know how annoying it is to work on your bike and accidentally set off the air horn? Bike mechanics like it even less because it's not even their bike. Many mechanics ask you to disarm your air horn before bringing it in. This has the unfortunate consequence of needing to remember to reinflate the reservoir before leaving the shop.
So do this:
A simple Shraeder valve cap will stick on top of your AirZounds air horn. It doesn't actually screw on, but when you push the button back down, it can't activate the horn, and the cap doesn't fall out.
Your greasemonkey can safely operate on your bike while you can ride home knowing you can scare the shit out of any pedestrian who walks into the street without looking first.