What if we could pee backwards? Hear me out! What if humans evolved a diaphragm for their bladder in order to create a pressure gradient, giving us the ability to 'suck' things up and store it in our bladder (as well as the opposite direction)? I mean, we already have pre-ejaculate fluid that balances the acidity between semen and piss, so theoretically couldn't I just stick my ♥♥♥♥ on a puddle of hydrochloric acid and slurp it up for emergencies? Like what if I'm getting mugged and I just drop my cargo shorts and tighty wighties, go full spread eagle on him, and coat his face in acid piss? I think this would be the smartest and most logical next step in human evolution.