Kids Riddles

Question: Draw, fire, or fill me;
I'm still empty.

What am I?

Question: what did the postman say to the mailbox?

Question: What do you call 2 Us?

Question: What is the easiest way to poke a balloon without popping it?

Question: I'll bring out your bulls,
and slow your roll.
I may even come out of your skull.

What am I?