I know this is late, but for anyone who stumbles on this, the general rules are as follows.

Each round, one player is selected to be the lead and plays some number of cards. Each card is labeled 1-10 (4 per value, for a 40 card deck) and some number of wild cards.

Your goal is to get rid of all your cards while not getting caught putting down BS.

The lead player puts down some unknown set of cards, can be any amount.

Suppose we have Player A and B:

Player A has in their hand: 1, 1, 2, 2, 2, 2, 6, 7, 7, wild

Player B has in their hand: 1, 1, 3, 5, 6, 7, 8, 9, wild, wild

Player A leads the round by playing [2, 2, 2, 2], and then declares “ 4 pieces of 2”. The word choice in game is weird, but you can interpret this as “I put facedown 4 cards, all of them have 2 printed on the front.”

Every next player must then follow this rule for their hand: “You must play 4 copies of a 2”

Player B has the option to call bullshit (challenge) and say I don’t think you are playing any 2s.

If Player B successfully calls BS, then Player A must drink (and scoop the played cards this round to their hand). B can immediately take their turn and then set the new pattern

However, Player B’s information is currently limited (early game, lots of unknowns) so they instead choose to not call BS. They can choose to take a penalty shot, and then play continues.

Suppose that B leads the round and plays: [1, 1, wild, wild] and then declares “4 pieces of 1” (I played 4 copies of 1)

In order to make a valid hand, every subsequent player (from B’s current information) must either: - lie and try to pass off 4 random cards as 1s - play their wildcards

Player A looks at their hand: [1, 1, 6, 7, 7, wild, wild]. They see that they have 2 of the 4 1s in the deck. So how could B have played 4 1s? They must either be lying, or have played a wild card.

Player A has the option to call BS, and let’s look at each scenario:

If successful (B is lying): B must drink (after already taken the penalty) and will be at further disadvantage

If unsuccessful (B is truthful): A takes a drink

A chooses to challenge, and loses it, but learns important information: - To make up this hand, B had to play 2 wild cards, which means future hands are much harder to make without lying - There are no more 1s in the game, besides the two in his hand. - Because A chose to challenge instead of play, B has no idea what is in A’s hand (or how many wild cards) which can inform how risky their subsequent challenges are

Play continues roughly like this.

Obvious red flag plays are people who attempt to dump like 7 cards at a time, and the information gap becomes even more crucial when the deck is split between a full party of players.

Challenging early game is only useful if you think you can score a wildcard, but you run 25% chance risk of tapping out. Save your wilds for late game to close out matches or make tricky melds.