Problem Statement: You find yourself needing to sit on a lot of hard surfaces, like floors, logs or bleachers, but your rear-end hurts after sitting on that hard surface for a while.
Solution: An inflatable air bag in the seat of your pants that can be quickly inflated and deflated using a mini pump in the pocket.
Key Design Concepts: The air bag system (pump, hose and bag) should be removable and/or washing machine safe. It should not be obvious that the air bag is there when deflated. Ideally, the pants would just have an internal pocket that the U-shaped air bag could go into, so you could own multiple pairs of pants, but only have a few air bags, which could be swapped out with ease. A premium upgrade might be to have an auto-inflate model that uses those little CO2 cartridges to keep the pressure in the bag.
A Side Benefit: I am not much into fashion, but I gather is some circles a well-rounded rear end is a fashion selling point. I would gather that a similar idea could be used in the fashion space, but I will leave that up to others to figure out.