What's interesting about this idiomatic expression is that although it might sound like it's cursing, it's actually not. There's also a great deal of intensity attached to it. It has a no-care tone, as if daring the world to turn the tides. And at the end of the day, you (the speaker who uses this idiom) will still persevere. For example: I will love him come hell or high.Come hell or high water, I will graduate with honors.This idiom simply means doing whatever it takes to reach a goal or make something possible.