have nothing between the/(one's) ears

have nothing between the/(one's) ears

To be rather stupid, dull, or dimwitted; to not have much common sense or basic intelligence. The expression is a way of saying that one has no brain. She seems nice enough, but I get the sense that she has nothing between her ears. Jake always goes out with really attractive guys that have nothing between the ears.See also: between, ear, have, nothing