I've heard of this before, but never knew what they were? Details, please? Thanks.
It's an undergarment that smooths out any lumps and bumps, so your pants/skirt/shorts look nice and smooth. They are made of spandex and usually go mid-thigh to above your waist, although there are different ones for different needs. I have several pairs in different lengths and colors - couldn't live without them!
Basically, they're an updated form of girdle.
In addition to the adult style Catherine C totally outlined...
The other style is what girls and cheerleaders wear under their dresses and skirts so that they can play without showing people their underwear. A tight fitting pair of shorts OR briefs, similar to bike shorts, but much, much shorter. Usually stretch cotton. Worn over underwear, under a skirt or dress. Meant to be seen / not immodest if they are seen.
Spanx is a brand but now people referred to any control garment as "Spanx".
