Ooooh I am jealous! This is a number one goal for me... which I might not reach, but I'd like to at least alleviate the situation.
It was 2004 when I had to start investing in bicycle shorts to wear under skirts because my thighs would chafe in the summer.

I'm sure they rubbed together before but that's when they reached the critical point! Also in the last year or so I've noticed I am destroying all my pants by rubbing out the inner thighs.
Anyways, congratulations! It's nice to know this feat can be achieved.