Off the top of my head
Posted by ESC on October 20, 2005
In Reply to: Off the top of my head posted by T on October 19, 2005
: Origin of "off the top of my head", does anybody know?
It means your first thoughts, initial reaction to a subject, etc. Its origin, in my opinion, is the view of consciousness being in layers. There's the subconscious. Then your first thoughts would be from a top layer or off the top of your head.