This excerpt from Practical Casino Math by Robert C. Hannum and Anthony N. Cabot ( two fellows).

A cooler used to be a regular deck of cards that the hustler(s) had on them to switch in after they beat a sucker to cool him off if he thought that the cards he were beat with were marked or gaffed.

I'd like to clarify what was stated above about a deck being cool or cold because it has not been played with. This is only my opinion on this, this maybe true to some extent but to me unlikely. Why? Us cheats have nerves to do what we do but don't think that we're gun ho to get beat up or die.

First off after we setup a deck in the bathroom we do place that deck in our pocket or on our body where the deck gets warm if it's not already. We are not and I repeat are not just going to go to a table without reservations or splashing and doing that move. Hence while we're waiting to execute the switch the deck is being warmed at that time by our body.

Yes I've seen decks of cards placed in a refrigerator freezer and handed to the players when they wanted a new deck to play with but a cold decker 99% of the time would never do such a stupid thing as switching in a (real) cold deck for a regular (warm) deck.

Respectfully,

Doc