play with a full deck

play with a full deck

1. To have the full faculties of one's mind; to be completely sane. Usually used in negative constructions. A: "Look at that guy talking to himself on the corner." B: He must not be playing with a full deck." I know you don't think I'm playing with a full deck, but I'm telling you the truth—a ghost came through the window and stole my briefcase!
2. To be bright or intelligent. Usually used in negative constructions. Mary's boyfriend is a nice enough guy, but some of the ridiculous things he says—I don't think he's playing with a full deck.
See also: deck, full, play
Farlex Dictionary of Idioms.

play with a full deck

 
1. Lit. to play cards with a complete deck, containing all the cards. Are we playing with a full deck or did some card drop on the floor? I haven't seen the three of hearts all evening!
2. Fig. to operate as if one were mentally sound. (Usually in the negative. One cannot play cards properly with a partial deck.) That guy's not playing with a full deck. Look sharp, you dummies! Pretend you are playing with a full deck.
See also: deck, full, play
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

play with a full deck

in. to operate as if one were mentally sound. (Usually in the negative. One cannot play cards with a partial deck.) Look sharp, you dummies! Pretend you are playing with a full deck.
See also: deck, full, play
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions

play with a full deck

Slang
To be of sound mind: didn't seem to be playing with a full deck.
See also: deck, full, play
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • take it with (one) (when one goes)
  • take it with one
  • mean (something) by (something)
  • mean by
  • change (one's) stripes
  • change one's stripes
  • change one's stripes/spots, cannot
  • put (something) past (someone)
  • anytime soon
  • have it both ways