Name something people say or do to test if a microphone is on?

People have quite a few ways of testing to see if a microphone is on. They all pretty much amount to doing something that will produce a sound that, if the microphone is on, will create an amplified sound coming from the speakers the signal from the microphone is being fed to. Some common examples include:

Say "Testing 123"

Tap it

Blow on it

Say "Hello"

Say "Is the mic on?"

Say "Is this working?"

Say "Can you hear me"

Say "Testing, Testing, Testing"

Occasionally people will say or do something off the wall.

One famous example of this occurred onn August 11, 1984, when United States President Ronald Reagan, while running for re-election, was preparing to make his weekly Saturday address on National Public Radio. As a sound check prior to the address, Reagan made the following joke to the radio technicians:

My fellow Americans, I'm pleased to tell you today that I've signed legislation that will outlaw Russia forever. We begin bombing in five minutes.