Answer:
A doctor might remove one from the neck of a Dracula victim.
What goes around and around the wood, but never goes into the wood?
You saw me where I never was and where I could not be. And yet within that very place, my face you often see.
Long and slinky like a trout, never sings till it's guts come out.
What goes in, but never through? I've got some and so do you. We might lend one, or even two, but only if our trust is true.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.