What does this expression really mean and where did it come from?
I'm assuming that it means you are just hanging upside down.
Maybe it means that your head is always hanging low and you are sad, but when you change your attitude, you're now looking up to the sky; holding your head high.
Best Answer
According to The Phrase Finder the expression 'upside down' is one of the oldest of the English language ( first part of the 14th century). It's meaning refers to :
The expression is common also in other languages:
It's original form evolved to become the current intuitive one:
One of the oldest English expressions: