Used as an intensifier after a question word (who, what, where, when, why, and how) to express extreme confusion, surprise, or aggravation. Primarily heard in US. And just how in thunderation am I supposed to have three reports done by 9 AM tomorrow? Where in thunderation did you find that rusty old car? Who in thunderation is making all that noise?
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.