I don't get it. Do women take them off just to put them back on around a single leg? If so why? Is it really that arousing?

In many images I've seen it doesn't even look like they're trying to be arousing but rather just get their cloths off and get to business, yet their panties are up around one of their thighs somehow. If they're around the ankle I can believe they dropped them then pulled a single leg out and didn't bother with the other, but when they're around the thigh or higher it's very hard to imagine them pulling a leg out while keeping the thing in place around the other.