in (the) Sam Hill?
Used as an intensifier after a question word (who, what, where, when, why, and how) to express extreme confusion, surprise, or aggravation. Often erroneously written or pronounced as "in Sam Hell." Primarily heard in US. And just how in Sam Hill am I supposed to have three reports done by 9 AM tomorrow? Where in the Sam Hill did you find that rusty old car? Who in Sam Hill is making all that noise?