Here's another off the wall pants idea from Naked and Famous Denim, the craziest jeans company in the entire world: Thermo-chromic denim. Jeans that change color depending on the temperature. Meaning if you get hot in certain areas (yeah, that too), the pants get whiter.
Naked and Famous have made its name in being the Willy Wonka of denim. Instead of regular, vanilla indigo, Naked and Famous have done glow in the dark jeans, scratch-n-sniff denim, jeans made with denim so heavy they could stand on their own and more. It's almost surprising that Naked and Famous didn't make these thermochromic selvedge jeans sooner.
The way the color changing pants work is like those color changing T-shirts from the '80s, the jeans are made using "a thermochromic dyestuff that has a molecule inside, which changes color based on its temperature range. The jeans start blue and become white with heat." It doesn't just react to body parts either, if the temperature is ridiculously hot, you'll have a pair of white pants. If it cools down, it'll revert back to blue. Check out how the jeans can change colors by just placing your hand on someone's butt: