Notice that if you turn your pants inside-out and put them on so the front is in the front and the back in the back, then you’ve got your right leg in the left pant leg and your left leg in the right pant leg.
Is there a way to turn very stretchy pants inside out while switching the legs?
Roll up the right pant leg over itself, stretch it over your head and over your left pant leg. Now you’ve got two pant legs on your left leg. Take the inner one, the one that was originally on your left leg and pull it up under the outer one. Stretch it over your head and over your right leg.
If your pants are really, really stretchy, then there’s another way where you take the pant legs around the world 🙂 .