You can still get moleskin trousers. It's a very fine, close weave pile fabric like velvet, so called because it was usually black and resembled the coat of the mole. It serves no other purpose that I'm aware of, than keeping your bum warm and giving you something to put your pockets in. It's soft and smooth, doesn't snag easily and can absorb a fair amount of moisture before your arse gets wet. They don't like the tumbledryer.