Question

to be one card short of a deck - He's one card short of a deck. There's no chance he'll be able to do it.  - Don't bothering asking her! She's several cards short of a deck.  - After they both looked at me like I was one card short of a deck, I explained about TV Ontario's online tutoring service.  - Nigel's description of the taxi driver being one bottle short of a crate was pretty accurate!

Accepted Answer

to be mentally slow; stupid A deck is a full set of playing cards. This expression is variable and used in a humorous way. E.g. He is several days short of a full month. She's one flower short of a bunch. They're two bottles short of a crate. And so on.

Idiom	to be one card short of a deck
Definition	to be mentally slow; stupid
Examples	- He's one card short of a deck. There's no chance he'll be able to do it. - Don't bothering asking her! She's several cards short of a deck. - After they both looked at me like I was one card short of a deck, I explained about TV Ontario's online tutoring service. - Nigel's description of the taxi driver being one bottle short of a crate was pretty accurate!
Note	A deck is a full set of playing cards. This expression is variable and used in a humorous way. E.g. He is several days short of a full month. She's one flower short of a bunch. They're two bottles short of a crate. And so on.

Short Card Deck She's I Full Mentally Slow