On a __; capriciously
I believe the answer is:
whim
(Other definitions for whim that I've seen before include "Fad" , "Caprice, sudden fancy" , "Capricious desire" , "Sudden impulse" , "Urge" .)
I believe the answer is:
whim
(Other definitions for whim that I've seen before include "Fad" , "Caprice, sudden fancy" , "Capricious desire" , "Sudden impulse" , "Urge" .)