Well, got to give him credit for trying to find out what it is instead of just talking the talk.

Double clutching is when you shift, you put the clutch in and put the car in neutral, then let the clutch out and rev the engine to where the rpms should be in the next gear, then push in the clutch, put it in gear, and let out the clutch.

The reason why you would do this is to get vehicle speed in gear and engine speed to match, so the transmission will actually shift.

Now, this is completly pointless to do in a modern car, because all that crap I said above is taken care of by syncros. Maybe on a car without synchros such as a 32 ford or a vintage pickup or a model A you'd need to double clutch, but not on anything you will be driving. The only exception would be if you have a bad synchro in one gear, and you'd only do it for that gear as a stop gap until you got that synchro fixed.

"Tutto fa brodo."

Todd Scungio
98 RS
15.173 @ 90.70 MPH

And also a 2011 Ralliart