Other euphemisms of this type (and there are many) include what in tarnation for what in damnation and what the Sam Hill for what the damn hell.

The ætern, ſempitern, everlaſting Spirit of Promiſs, Life, Comfort, of Feith, Truth, Holineſs, of Grace, God, and of Glorie, teſtifieth, beareth record, and ſetteth it Seal to the Truth of Thour being the alone Autor of al Salvation.[…]: evn ſo I mi veri ſelf, O wretched man of men that I am, did hood-winkt, blind, blind-fold run, tumbl, ruſh throuh al manner of evils, when the briht, beuteous, fair liht of Thour bleſſed Spirit expanded it beams magnificently, ſpread forth it raies gloriouſly, ſhined reſplendently and directed, pointed, ſhewed me the vaie leading to the ætern Kingdoms of the bleſſed Cœlestial Inhabitants.

Though the fad ran its course long ago, the phrase “pet rock” endures in the American lexicon, denoting (depending on whether it is uttered with contempt or admiration) a useless entity or a meteoric success.]

You're a brimstone idiot.