i ve been using this trick for a while and they dont even ask you to hand them the deck (you can, its a regular deck) sometimes...
I completely agree -- every time I perform Panic, I hand the deck out to spectators after it reappears in my back-pocket, and they rarely ever inspect it (though they can if they like). Usually, they just check to see that it is, in fact, a real deck -- and it is.
Panic is so strong and visual that, from my experience, in the mind of the spectators there is nothing really to inspect -- the deck vanished in my hands, leaving the four kings, and reappeared in my back-pocket; it couldn't seem any cleaner. What little cleanup there is, happens easily, subtly, and goes unnoticed.
Definitely an amazing effect -- and I, personally, am in love with the Panic gimmick. It still astonishes me, every time I use it.
[End of mini-review.

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Cheers,
JTM