Think about it. Your character will have to poop and pee, like real life. There will be a brown glow around your food HUD icon that gradually gets darker over time, eventually getting very dark, and then flashing just like when you are starving or dehydrated. At that point, you may poop randomly at any moment, and be vulnerable for a certain period of time (20 seconds? 30 seconds? a minute?). The same goes for peeing; there could be a yellow glow around the water icon that eventually flashes if you've not satisfied your need to pee for a while. You will then pee (your pants? then there would have to be some sort of speed debuff, but i'm not sure if debuffs are a good idea for this – making yourself vulnerable for 10 seconds is enough). Imagine killing a bandit that's been stalking you for the past 10 minutes, then walking over to his body and taking a shit on his face. Think about sneaking up behind your buddy while he's afk then unzipping your pants and peeing all over him right when he comes back. Maybe if you pee on somebody's face it can blur vision temporarily & has a chance to cause infection/disease (Rocket mentioned the temperature system may implement some sort of sickness, could coincide with that). If you contract some sort of sickness, your poops will be irregular – maybe you can get constipated, or even have projectile diarrhea spray up to 2 feet away. Poop decals are, of course, required. If you eat beans, you may get super farty and have to fart every so often. The noise could reveal your location. This would give value to different food sources (so pasta/sardines/beans aren't all exactly the same) – ones that make you fart less, or have less diabolical poops. For pooping, maybe you will need to carry around toilet paper – if you can't find any, you can use bandages, or you can get a speed debuff from chafed butt. This is all I can be assed to write right now, but I may come back later and add. I think it's a pretty amazing idea, and I've always wanted a game where I could poop and pee realistically. Let me know what you think & feel free to discuss! :)