has been mentioned in the threads on Double Back -
http://www.talkmagic.co.uk/viewtopic.php?p=16640#16640 - and TT Tone -
http://www.talkmagic.co.uk/viewtopic.php?p=16639#16639 - and is the keynote to most effects. Having the guts to do it, the sheer brass nerve to get away with it and similar, but far less repeatable, phrases could be used.
Practice is paramount as this brings the confidence to do something which the specs won't see. As an illustration, there was a programme on Sky a couple of weeks ago where Lance Burton showed a few of the secrets of magic (but nothing really startling) as an illustration of how science, misdirection and optical illusions are used regularly in magic.
He took a deck of blue backed Bikes, cut them about half way and asked the audience to count how many red cards were being dealt. He then dealt all the cards in the lower packet face up and, along with millions of others, I counted and got 17. Lance said there were probably about 17 or so but the thing which was far more important, all the cards dealt had red backs therefore all the cards were red. And the cheeky thing was that the only blue backed cards used were the top one and the one cut to halfway down. The rest were all normal red back cards and, when the trick was re-run, this could be seen clearly, right under the collective noses. All our concentration was on the face up pile and counting the red suits so we just didn't see the red backs being shown openly. Marvelous misdirectional stuff and I was caught, hook, line and sinker. A lesson well learned and never to be forgotten!