I have a good friend who thinks in a very concrete way...On a recent cycle tour, we were talking about owls. One of the group was explaining that a common misconception about owls is that they're wise - in fact they have very small brains because most of their head is taken up by the eyes, being very big in order to see at night. So, speaking metaphotically, he said 'the eyes are so big, there's no brain in there', so my friend immediately jumps in with the question 'so where's its brain then?'. A sensible question, one might think, except you were supposed to get the subtle metaphor...
Later in the same tour, we were discussing something or other and another one of the group mixed up the phrase 'elephant in the room' with 'skeleton in the closet' and ended up saying 'elephant in the closet'. Whether you're describing something big and unmissable or quiet and hidden, cramming an elephant into a wardrobe in the process aint going to get you very far...