What would happen if we did not use time zones

The world would operate in a very confusing manner without timezones.

The planet itself didn't care about timezones, as they are a human invention. But because the Earth is generally known to be spherical, that means all humans are scattered across it without a uniform method of keeping everyone in sync, which would wreak havoc on international shipping and travel. People wouldn't know what you mean when you say that you'd all Skype call with each other by 10pm, and planes coming in at 5am would have no context on what that time means, because there are no standards for time anymore.