The girls never take off their sunglasses

I don't know if this has been mentioned before, but I just watched an episode of 'How I Met Your Mother' in which Ted says, "Like the top 1% of the population that always wears sunglasses no matter where they are or what time it is." In this one episode, Ted encounters two attractive girls with sunglasses in a bar that are also wearing sunglasses inside. Then a little later, when he's at home with them, they keep their sunglasses on. I think this was in a lot of other episodes too.