What defines on?

Although this meaning is often used in TV, radio, and the stage, it could also be used during a con scam (as in the movie), or even in marketing.

At an expo, for example, one of my associates might be getting ready to demo our product, and I might say:

Okay, you’re on, right? Generally, people look sharp. They can easily look smarter as well.

Can you be around now, my daughter is

giving a speech? Practice one more time, and get a good night’s rest.

If I want to stand my ground against China’s economy, then I just need to create this!