What does hotter than sam hill mean?
"Sam Hill" is a euphemism for the place where Satan lives. That would be really hot.
There seems to be no association of the phrase with an actual "Sam Hill". Suggestions of a connection with the millionaire Samuel Hill are clearly erroneous as the phrase was in use long before he came to prominence A more likely explanation is that it is a corruption of "Samiel" in reference to the Devil.
"Sam Hill" is a euphemism for the devil or hell and dates from the early 1800's. One possible origin is from Sam Hill's Mercantile in Prescott, AZ, which claimed to sell just about everything you could imagine. Another possible origin is surveyor Samuel Hill, who allegedly used such foul language that his name passed into general usage.