1
general::
Phrase(s): fit to kill
Rur. a great deal; to the highest possible degree. • We laughed fit to kill when we saw the expression on Jim’s face. • I had my car gussied up fit to kill.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Excessively, immoderately, as in She was dressed up fit to kill. [Colloquial; mid-1800s] Also see DRESSED TO KILL.
American Heritage Idioms