by Alan Townendthem «hang their heads» — feel ashamed. Other emotions can also
play their part. A couple are «head over heels in love» —deeply in
love with each other. Their two sets of parents perhaps «put their
heads together» (discuss the situation), «scratch their heads» (can't
understand why their children feel as they do) think the two of them
are «weak in the head» (not thinking properly), want to «knock the
love affair on the head» (put a stop to it) but remembering that they
too were young once, decide to «give them their head» (let them do
what they want).
«Off the top of my head» (without further research or thought), I
was going to say that's it but I'd forgotten the expressions to do with
the removal of the head. «Talking your head off» is to talk
incessantly. After an investigation into bad practices within a
company or organisation when certain individuals have been found
guilty and they find themselves in serious trouble, then the general
feeling is that «heads will roll» — they will lose their jobs. And finally
when you panic and act in a stupid way, you could be described as
«losing your head». And this is what happened to Charles 1st (King
of England, Scotland and Ireland 1600—1649) who rather foolishly
wanted to rule without Parliament and caused the Civil War. Poor
chap he lost his head both metaphorically and literally — he had his
head cut off.