Help: Las Vegas trick deck

[Pifflet]

So I stumbled upon my dusty old box of magic tricks today and I found a deck which contained used Casio cards from different casinos in Vegas. Now the entire deck was made up of the jack of spades except for two blue backed 6 of diamonds and two red backed 6 of hearts.

I cannot remember even slightly what the trick actually was or any sleights of hand involved and it's really been bugging me because I remember it was a really good trick and it's pretty cool that the cards were actually used in Vegas.

So if anyone knows this trick or it rings a bell for anyone help would be appreciated.
Thanks

 

[Josh Burch]

I recieved a similar deck to this from a local magic shop. They didn't carry one way decks and so they gave me one of these with bicycle backs. I glanced at the instructions before I destroyed the deck. It had something to do with forcing 2 cards showing that they had changed colors and then revealing that all the other cards were of one value. I don't remember the specifics though.