1
general::
Phrase(s): on earth [and] in creation; in the world
Fig. really; indeed; in fact. (Used as an intensifier after who, what, when, where, how.) • What on earth do you mean? • How in creation do you expect me to do that? • Who in the world do you think you are?
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Also, in creation;in the world. Ever, anywhere, of all possible things. These phrases are all used for emphasis in questions or, less often, in a negative context. For example, What on earth is he doing with a spade? or Where in creation did that child go? or How in the world do you expect me to carry all those bags? [Late 1700s] 2. like nothing on earth. Incomparable. For example, That perfume smells like nothing on earth, or Her new hair color is like nothing on earth. [c. 1900]
American Heritage Idioms