Answer:
You use it between your head and your toes, the more it works the thinner it grows. What is it?
What has no hands but might knock on your door, and if it does you better open up?
Can describe a distress signal or flashy accessories.
What kind of cup doesn't hold water?
Ambitious people will climb the social version of this contraption.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.