RichThesaurus
doolally
vs
off one's rocker
doolally
adj
Eccentric; insane, mad.
Carried away by enjoyment, excitement, etc.
off one's rocker
prep
Crazy; insane.
How often have the words
doolally
and
off one's rocker
occurred in a corpus of books?
(source:
Google Ngram Viewer
)