Pushing the Envelope

Suppose you are a test pilot. You are given a new plane and told to test it. You are also told how fast it is, how well it turns, how high it flies, etc. In aeronautics, that information is known collectively as the "performance envelope."

Now suppose you take that plane up for a ride and you notice that you can get a little more out of the plane than those dumb engineers told you. So you push the plane to its limits to see if you are right. That's called "pushing the envelope."

Nowadays, anybody who tests the limits or restrictions of something can be said to be pushing the envelope.

I'm going to wrap this up. I wouldn't want to be accused of pushing the envelope beyond the limits of your patience.