Answer:
What is as big as you are and yet does not weight anything?
What is given but kept by the giver?
A great mysterious place that the bold have been known to journey into.
Gets rid of bad ones, short and tall. Tightens when used, one size fits all.
I am never quite what I appear to be. Straight-forward I seem, but it's only skin deep. For mystery most often lies beneath my simple speech. Sharpen your wits, open your eyes, look beyond my exteriors, read me backwards, forwards, upside down. Think and answer the question...
A red house is made out of red bricks. A blue house is made out of blue bricks. What is a green house made out of?