off on

off on someone or something

in a rage about someone or something; on a tirade about someone or something. Are you off on Sally again? Why can't you leave her alone?
See also: off, on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • check off
  • be off for (something)
  • be off for sth
  • cadge (something) off (someone)
  • cadge something off someone
  • bum (something) off (someone)
  • bum off
  • bum something off someone
  • (I've) got to take off
  • break off