Liar's dice · since the 16th century

Dudo

Five dice, one cup, and the oldest question at the table: do you believe them?

Dudo — Spanish for “I doubt it” — is a bluffing game played across Peru, Chile and Bolivia, where it is also called Cachito or Perudo. Every player hides five dice under a cup and bids on how many of a given face are on the table, counting everybody's dice, not just their own. Nobody can see enough to know the truth. That is the whole point.

How a round works

Everyone shakes their cup and peeks at their own five dice.
The first player makes a bid: a quantity and a face, say four fours.
Going clockwise, each player must raise the bid — more dice of the same face, or any quantity of a higher face — or call dudo.
On a call, every cup is lifted and the matching dice are counted.
If the bid was good, the doubter loses a die. If it was not, the bidder does.

A player who runs out of dice is out. The last one still holding a cup wins.

Aces are wild

Ones — aces — count as any face. This single rule is what makes the arithmetic interesting: with thirty dice on the table, the expected number of threes is not five but ten, and beginners who forget it bid far too cautiously for the first few rounds.

Dice in play	Expected count of a face	Safe opening bid
10	3.3	3
20	6.7	6
30	10.0	9

Calling aces. A bid made in aces alone needs only half the quantity, rounded up. Switching back out of aces then costs double plus one — which is why the ace bid is a weapon of last resort, not an opening move.

Three habits of good players

Bid your own dice first. An honest bid you can partly back up is far harder to read than an invented one.
Watch the hesitation, not the face. The pause before a raise says more than the number that follows it.
Count down, not up. As dice leave the table the expected counts fall fast, and the player still bidding as if it were the first round is the one about to lose a die.

Where it came from

The game travelled from Spain to South America in the sixteenth century and settled into local form along the Andes. The English-speaking world met it as liar's dice, and it has been reinvented as a board-game edition, a pub game and, inevitably, an app — but the version worth playing is still five dice, a cup, and people who know each other well enough to lie convincingly.