Answer:
Always in you, sometimes on you. If I surround you, I can kill you. What am I?
I row quickly with four oars but never comes out from under my own roof.
You use me between your head and your toes the more I work the thinner I grow.
We applaud if you perform well.
My full powers come when my makers are dead. I await a heavy hat to put on my head. What am I?
I flow from the Homerβs mouth when he sees doughnuts.