be not playing with a full deck

be not playing with a full deck

1. To not be mentally sound; to be crazy or mentally deranged. A: "Look at that guy talking to himself on the corner." B: "I reckon he's not playing with a full deck."
2. To not be very bright or intelligent; to be dimwitted. Jim's a nice guy, but with some of the foolish things he does, I wonder if he's not playing with a full deck.
3. To be acting deceptively (as if one is playing with a deck of cards after having removed some of the cards from the deck). I doubt that Brian's playing with a full deck—how could he win so much money without cheating?
See also: deck, full, not, play

be not playing with a full deck

mainly AMERICAN
If someone is not playing with a full deck, they are not being completely honest and therefore have an unfair advantage over other people. This guy is either very good or he's not playing with a full deck. Note: A deck of cards can have cards taken out before a game in order to give one player an advantage.
See also: deck, full, not, play