Women in Comfortable Shoes

I really want to understand what the etymology of this phrase. I've looked everywhere, I've heard it used by lesbians themselves, but I have no idea where it comes from.

I promise votes to a good answer ;-).

What is a protective dike? Is that a large woman standing by the river going, (deep voice) "Don't go in there!" (redneck voice) "But Betty!..." (deep voice) "Don't go in there! Stay away from there! Don't go in there!"

I know, you can't say the word "dyke" anymore, you can't even say "lesbian", it's "women in comfortable shoes." Thank you very much!

-- Robin Williams as Adrian Cronauer, Good Morning Vietnam