Bear grease/oil. If you haven't killed one lately, get your buddies or taxidermist to save you the pretty snow-white fat, cut it into little pieces and render down just like you would pork skins. Grease your ... area ... crack and all with it, you won't sweat-gall, and if you have to do what the bears do in the woods you'll find the cleanup a lot easier, especially if you don't have toilet paper.
If you don't like the smell, add some saffrasass root and either cinnamon or bayberry oil (careful with that last one, it's strong).
Another advantage is if you put it all over your body (I save the "crack" for last if I'm doing that) you'll stay warmer, it's about like adding a thin pair of long johns. If you get wet your skin won't soak and shrivel, and it'll dry faster. I keep the bottle handy when I stay in the woods at night, a thin coat on my head keeps me as warm as a light toboggan.
It keeps off bugs, too, if you add the sassafras and cinnamon.
It's the best gun oil yet, that's all my flintlooks ever see and they don't rust in the rain.
Did I mention that it's good for frying meat in, too? Just the plain bear oil - for some reason it doesn't get rancid like other oils and lards.