it's just cos earth is proportionally so big to your body that it makes you think you'r living with you head UP. like if a flew would sit on the downside of a pumpkin. (read that comparison in a book once ).
but face it - in fact you aussies live upside down
Actually we don't really.... coz gravity pulls from the centre of the earth so wherever you are you're upwards. But we are kind of upside down I spose lol.