I occassionly stumble across an expression like "What the Sam Hill...?" (U.S.). Though it's quite obvious another way to show great surprise or disgust while at the same time avoiding the use of "hell", "heck" or even worse four-letter-words, i still wonder about the origin of the phrase. Is it simple courtesy, mostly used in the "Bible Belt" or did some evil guy by this name really exist (australian mountain bikers excepted)? Thanks in advance .
Thank you, soup, for your quick reply and linking! Jodie44's answer is very detailed and fun to read.