This week’s idiom is one that is used to talk about a person that is perhaps missing something in the brain department. Actually, there are numerous expressions in British English that can mean a similar idea. To say things such as that someone is a “few pennies short of a pound”, or “not the brightest bulb in the box”, it is to say that they have a lack of intelligence.
But probably the most common among these types of idioms is describing someone as “not playing with a full deck”. “Deck” in this case refers to a deck of playing cards, rather than the area of a ship.
“I don’t know if he’s playing with a full deck, last night he said he didn’t know who The Beatles were.”
“The poor guy, he’s not playing with a full deck. Anyone could see that that was a foul.”