- The U.S. Forest Service defines this as "a burn by a surface fire that can consume ground vegetation and 'ladder' fuels." Since they get paid for what they do, it probably means something.
- Partially-cooked food.
- The sensation you get from the lower part of your body after you've eaten something you shouldn't have.
- The sensation you get from the very bottom part of your body the day after you've eaten something really really spicy, and it's suddenly leaving you to set out on its own.
From: Fire In Your Hand