reason why i sag is because frankly wearing tight enough pants that stick in the same spot all day isn't comfy i let my pants hang a little nothing so my buttocks is completely hanging out but enough so my pants aren't above my pelvis. The reason why my boxers are worn higher up than my pants is because i find the pants touching my hip skin irritating and i don't find it comfortable so i simply have my boxers slightly higher because boxers are far more comfortable than jeans. On how skating with pants lower is more comfortable. I used to skate and ive noticed that leaving more legging for my legs to move constricts them less when i did tricks so i would wear them lower and simply wear a belt so they would stick to one general area.