That happens very rarely to me, but whenever it does it always happens on the streets when I am performing. What I do is simple, if it pops out I square up the deck and say, "You saw that card there yeah? the one upside down? Well this time I want you to take it...". I follow this on by going through and getting the right card this time. Nobody has ever noticed this, and it never goes wrong twice in a row for me

(luckily)
Also, they asked to examine a card

. I just gave them the top card without letting them see the card "underneath" so to speak
I do hope that that has helped you
