Answer:
I hide but my head is outside.
In the evening I'm long, in the morning I'm smallΝΎ When seen in a ballroom, I'm nothing at all.
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
What flies forever, Rests never?
It's anything but amusing when this body part gets hit.
What is so fragile that saying its name breaks it?