Answer:
I hide but my head is outside. What am I?
I mean goodbye for South Americans.
I am a portal to another world which you cannot enter. Only you can see me but I can't see you.
If you drop me I'm sure to crack. But give me a smile and I'll always smile back.
I am a mountain at night meadow at day
I go in hard, come out soft. Blow me hard and I'll make a pop. What am I?