

Why: waistband cut high around the waist makes bum look bigger because there is more fabric.
or
Why: make your ankles slim, but Jesus, does your arse look enormous above them.


Why: the lower waist-band cuts the bum area in half making it in turn half the size.
alternative
Why: keep it all well balanced, as they don't so much cup the bum as hang softly away from it.