Women with long, slender legs can cross them and uncross them at will and how they like. There is a sound rule for the rest:
cross your ankles and only your ankles and, even then, only if you cannot control yourself enough to sit with your feet uncrossed and gracefully placed on the floor - both of them, side by side or one slightly behind the other for an occasional shift in position.
Women who are not wearing men's clothes should follow the rule and stop displaying fat thighs, in cheap tights, crossed above the knee. And yes the cheapness of tight can be spotted from a distance, and through a television camera.
And sit up straight while speaking to others. Or stand up; which has the great advantage of taking the attention off fat legs, except for the truly gross.
The BBC on high school philosophy in France
11 hours ago