When a card is pushed to a receiving player, they have two options.
They can issue a challenge by agreeing or disagreeing. For example,
“I’m challenging you, you’re telling the truth” (agree)
“I’m challenging you, you’re telling a lie” (disagree)
And then the game moves on to the resolution stage.
Otherwise, if the receiving player is unsure and they don’t want to challenge, they can pick up the card, look at it and push it to a player stating a colour.
This can be the same colour that has been previously stated or a different colour. For example:
“This card has orange on it”
The latest receiving player has the same options. They can then either agree, disagree, or pick up the card and push it on again. This carries on until a player issues a challenge by agreeing or disagreeing.
Then the game moves on to the resolution stage.