Sam Hill is an American English slang phrase, a euphemism or minced oath for "the devil '' or "hell '' personified (as in, "What in the Sam Hill is that? ''). Etymologist Michael Quinion and others date the expression back to the late 1830s; they and others consider the expression to have been a simple bowdlerization, with, according to the Oxford English Dictionary, an unknown origin.
where does the phrase sam hill come from
unknown origin