If this kept the skirt from also turning into shorts, it would be even better. Make this into a skort version and you'll have a million dollar idea, Jockey. Remember who told you, though.
I wear these under slips (and skirts, of course) with undies underneath them to keep my thighs from sticking together on a hot day. Or even a cold day. My thighs like each other too much and are very close to each other. They are a bit smothering, to be honest, with their affection of one another. These slipshorts help a LOT.
UPDATE: I've had these now for a couple of years and they are still going strong. I have never had them ride up, roll down, wedgie, or do anything weird. In fact, I wish all my clothes would stay put the way these do. I read other reviews that say that rolling or riding is a factor, but I think they must have the wrong size or something. I am 5'3"ish and weigh about 140 and my thighs are pretty..well... thick. If J. Lo and the Rock had a baby, the baby would be about the size of one of my thighs when it got to be about 2 yrs old. The Medium fit me perfect and has continued to fit through weight gain and loss. Still highly recommend.