Card caps aren’t worn on your head because they aren’t hats.
Back when the first legal casinos opened in Nevada, the state legislature established a Gaming Commission to promulgate rules and regulations for play. The Commission is still there and still in charge.
An early rule that is still in force today is that any poker hand that touches the muck pile or any cards being mucked, is dead and becomes ineligible to win the pot. The purpose of this rule is to prevent cheating by players swapping cards into or out of their hands during a game to produce a winner.
As always, execution is everything. Suppose two cheating players were in a hand with you, betting and raising, and you put your cards down on the table to count out the chips for a bet. While your cards were tabled and your hands were away from those cards, another player suddenly says “I’m out,” out of turn and throws his cards on top of yours.
Guess what? Your hand is now dead. It touched the muck. Furthermore, any chips you’ve put into the pot are now forfeited. There is no appeal on this. Each player must guard his own hand at all times.
There are times when it is impractical to bet with only one hand. Since players aren’t allowed to remove their cards from the table, how can they solve this dilemma without risking having their hands mucked? They can put a bunch of chips on top of them, Or…they can put a small weight on top of their cards so no foreign card can be mistakenly mixed with the player’s hand. That weight is called a card cap, a poker weight, or a card guard.
Many live players use a card cap for luck, some do it from habit, some for fun, or to show their individuality. Some just put a chip or three on top of their down cards. Some caps are fairly elaborate.
I saw one that looked like a scale model of a trailer-truck and another like a train’s locomotive and tender. Monopoly game pieces, especially the top hat or the race car, have been used. Lots of coins, especially half-dollar and one dollar silver coins, have long been popular for their convenient size and weight.
My current personal card cap is a “challenge coin” the size, weight, and shape of a US Half Dollar, but bearing the image of the USMC Eagle, Globe, and Anchor. Before that I used a polished 3/8″ thick marble slab the size and shape of a business card, but it was too large and heavy to be practical (it also tore holes in my pants’ pocket).
The oddest one I can remember was about an inch thick and an inch and a half across, made of a heavy, perhaps leaded, glass with a Black Widow Spider embedded in it–and used by a little old lady in Connecticut who looked like butter wouldn’t melt in her mouth on a summer day. (I doubt it was a real spider as the molten glass would’ve instantly burned it to ash on contact.)
Do you use a cap? What is it, if you do? What’s the strangest one you’ve ever seen at a table?