Where on earth?

where on earth

An emphatic way of forming any statement or question beginning with "where," typically when expressing frustration, anger, irritation, incredulousness, etc. Just where on earth do you think you're going? You've got school in the morning, young lady! We're not going anywhere until I figure out where on earth I left my wallet. I don't know where on earth you got so much money, but there's no way you earned all that just from flipping burgers on the weekends.
See also: earth, on
Farlex Dictionary of Idioms.

Where on (God's green) earth?

Inf. (Exactly) where? (An intensive form of where. See examples for variations.) Where on God's green earth did you get that ridiculous hat? Where on earth is my book? Where on God's green earth were you?
See also: on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

Where on earth?

verb
See Where on God’s green earth?
See also: on
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • where (in) (the) hell
  • where (in) (the) Sam Hill
  • Where in Sam Hill?
  • Where in the Sam Hill?
  • Where in the world...?
  • Where in the world?
  • who (in) (the) hell
  • who in the world
  • who the deuce
  • Who the hell?